Original subtitles

Let's face it - our world is downright weird.

Aaaaaah!

Crawling with creatures you've never heard of.

I can't believe that's a living thing.

Full of the unexpected,

like freak weather exploding out of the blue.

I thought I was going to die.

And rocks that spontaneously combust.

I thought it was dynamite going off.

And the unexplained.

An unborn twin...

discovered inside a brain.

There was multiple hair follicles, bone and teeth.

We scoured the globe to bring you the very weirdest stories.

Yeaaaahhhhhhh!

Ha-ha-ha-ha-ha!

I could feel this intense pain,

as if you were being stabbed by hundreds of syringes.

In this series, we're going to examine the evidence,

test the science and unravel the mysteries.

We're going to discover what in the weird world is going on.

In this episode, we'll uncover the mysteries

behind some of the natural world's strangest stories.

What could have caused this shadow in the sea?

Immediately, we thought it was an oil slick. What else could it have been?

And what is making this lemming so angry?

How could a shoal of fish almost cause an international incident?

And how can a man see with his ears?

I am a man who uses the techniques of a bat to navigate.

Out here in the desert, people often report seeing mysterious things -

mirages, strange lights in the sky, UFOs.

But it does seem wherever we are,

our surroundings are capable of playing tricks on us.

July 8th, 2014 - La Jolla, California.

So it was a stereotypical sunny San Diego kind of day -

the sun was out, the water was clear,

tourists everywhere enjoying the beautiful weather we normally have.

But all was not well in paradise.

There was just something really unusual going on.

We looked out and saw this black blob in the water.

A huge, oily black mass had appeared along the coast,

stretching for miles up the beach.

I left my office and ran towards the pier

so I could see first-hand what was going on.

Immediately, we thought it was an oil slick. What else could it have been?

This wouldn't be the first time that an oil slick has hit California.

Just off the coast, there are some really rich wells

so oil's been washing up on the beaches since the 1950s.

But from above, there was something very fishy

about this particular oil slick.

It looked like oil, but it wasn't behaving like oil.

We didn't see any oil residue on the sand,

which, for that big an amount of black,

we definitely should have seen oil on our surface.

Even stranger, it seemed that the oily blob

was actually being repelled away

from people and animals in the ocean.

So what exactly was this suspicious slick

and why wasn't it washing ashore?

From the pier, the truth suddenly became clear.

Once we were able to look down, we realised,

"Oh, my gosh, this is just a huge school of fish!"

Amazingly, the giant black mass in the ocean wasn't oil.

The coastline had been invaded by an immense silvery shoal of fish.

From below the waves, it was clear what had swamped the shoreline.

Anchovies - perhaps as many as 100 million of them.

It was quite phenomenal.

I've seen pictures of schools like this,

but I've never got in the water with them.

It was like diving into a large dark blob

and having it separate as you went inside of it and create a cavity.

It had a life of its own, you might say.

For a shoal of this size to be so close to shore was truly strange.

I've never seen anything like this before in the 30 odd years

that I've been in this area.

We don't know exactly why the anchovies were here,

but anchovies tend to school in order to avoid predators.

Anchovies are part of a group of fish called obligate shoalers

that live almost exclusively in deep waters.

However, a large group of predators could have forced them inshore.

But with all the swimmers in the water, this seemed unlikely.

And it was about to get weirder

because it wasn't just fish that were being driven inshore.

Look at these guys! Just absolutely crazy.

Just a short distance down the coast,

the surf turned to an eerie red.

Not with blood, but with a plague of red tuna crabs.

The whole beach is covered with them.

Hundreds of thousands of tiny red crustaceans carpeted the beaches,

littering the landscape with stinking piles of seafood.

And this wasn't the only stranding.

All across the state, abandoned sea lion pups were washing up

in unexpected places and one scientist thinks she knows why.

Something really weird is happening

off the coast of California at the moment.

So we've detected this anomaly out in the ocean

and we've called it The Blob.

It's enormous, thousands of miles across, hundreds of metres deep

and we think it's getting better.

What scientists had discovered was an immense blob

of abnormally warm water, squatting off the Californian coast.

It was so large that it could be detected by satellites in space.

It's water that's about four degrees Celsius warmer than it should be.

It began off the coast of California and it's moved inland,

it's invaded the beaches all along the coast.

Now, a bit of warm water might not seem like much of a big deal,

but many marine animals are highly sensitive

to alterations in their environment

and four degrees warmer is a big shift.

By changing the temperature of the water beyond what it should be

at this time of year, it's shifting the whole food web in the oceans.

This shift has forced many of the local species to find new homes.

Tuna crabs venturing too close to the shore,

sea lions pushed further out to hunt, leaving their pups to starve

and anchovies searching for cooler waters,

swarming along the shoreline,

all down to an oceanic abnormality.

It's still a really big mystery as to what is causing The Blob

and why we've got this huge area of warm water off the coast

and scientists are trying to figure it out.

And while the mystery remains unsolved, it's a safe bet

that the residents of La Jolla Beach can expect to see

more weirdness in the waves sometime soon.

So it appears that a giant shoal of anchovies

can masquerade as an oil spill. Who'd have thought it?

But then, what other weirdness

might result from an aquatic case of mistaken identity?

How about...a military fallout between countries?

In the 1980s,

strange things were happening in the waters around Sweden.

Nato and the USSR were still locked in the Cold War.

And Sweden was caught in the middle,

right next to the Iron Curtain.

Soviet submarines were on patrol.

It was a very, very tense situation.

Everyone was terrified

because we thought we were being occupied by the Soviet Union.

Throughout the '80s,

Soviet subs were reported regularly off the coast of Sweden,

so the Swedes set out to trap them.

They started monitoring their coastline

with underwater microphones.

The navy drew up a list of signs and sounds

that might indicate stealthy submarine activity.

When you listen underwater, it's a whole new world.

You hear all kinds of things.

They could hear engine noise, for example,

boat engine noise or they could hear Russian submarines.

One of the sounds the navy typically detected

that indicated a Russian submarine,

they called, imaginatively, "the typical sound".

CLICKING AND WHIRRING

Although civilians weren't allowed to hear it.

Everyone sort of knew that the typical sound

was the sound of a Russian submarine.

We could never hear this sound because it was classified,

but we all heard about it.

But when the Cold War finally ended,

something really weird started to happen.

The Swedish thought that they could

still hear Russian submarines in their waters.

The Swedish navy still consistently reported,

"We are still intruded by Russian submarines.

"We hear the typical sound all the time."

But the Russians claimed they hadn't sent any subs.

So, were the Russians actually telling the truth?

And, if they were,

what was the typical sound that the navy was listening to?

Clearly the Swedish authorities needed to get to the bottom

of this marine mystery before it was too late.

So the Swedes called in acoustic experts like Magnus

to try and identify the typical sound

and help defuse the situation.

This is when we were actually able to hear the sound for the first time

and we were then the first civilian people

ever to hear the typical sound.

Then they played this sound for us

and we were all sitting quiet in this room, listening carefully.

HISSING AND POPPING

It sounded like someone frying bacon.

And I was like, "When are you going to play the sound?"

And they were like, "Well, we just did."

HISSING AND POPPING CONTINUES

That's an underwhelmingly odd noise.

I suppose it just about qualifies as a mysterious sound.

Maybe the Russians had a penchant for undersea stir-fry.

Or could it be a red herring?

Weirdly, that's exactly what Magnus thought it was.

It didn't sound like a submarine at all and he could prove it.

We recorded this sound and it sounded exactly like this typical sound

so we sent it back to them and they told us,

"That's very interesting, where did you get that from?"

"It's from a herring."

He used a herring to make the typical sound.

But how could the noise that a herring makes

possibly be mistaken for the sound of a Russian submarine?

Well, probably not how you think.

There's only one way to produce the typical sound

and that is to squeeze a herring.

Yes, that's right, you heard him - squeeze a herring.

So, herring is a very interesting fish. It has a swim bladder.

The herring will pump in air into the swim bladder to sort of keep afloat,

but the funny thing with the herring is that has a canal

from the swim bladder and out to the anal opening.

See where this is going yet?

So they can sort of...fart, if you want.

And each time they release these bubbles, that will cause sound.

And although one flatulent fish couldn't cause a crisis,

a whole farting school could.

So you can have millions and millions of herring,

one school could be like several square miles.

I have seen it sometimes when you're out sailing

and you can have hundreds of metres covered with just bubbles everywhere.

You have this cacophony of farts coming

and you will hear, like, a roar of farts coming

and it can actually sound quite impressive.

Impressive indeed! In fact, I wish I'd heard it myself.

But why on earth would the navy think

that it was the sound of a submarine?

Well, the answer lies in the reason why herring make the bubbles.

They use this as what we call an anti-predator defence,

so if you have a killer whale or a dolphin chasing a herring school,

they can release a lot of air and a dolphin is like,

"Hey, where did the herring go? I can just see bubbles now."

And to a school of herring, an underwater sub can be just as scary.

During the Cold War, Russian subs had been cruising past

schools of herring and causing them to panic,

causing them to make the typical sound.

If one of those guys enters a herring school,

they will probably scare off the herring

and you will hear a lot of those sounds.

And after the Cold War ended,

the herring continue to make these panic sounds,

but this time, they were scared by predators.

Or, embarrassingly, by Sweden's own submarines.

If you think about this guy moving through the water,

all the herring will be scared

and probably release all these bubbles

and the sonar operator inside here, he will be like,

"I can hear the Soviet submarines just next to us."

So instead of tracking Russian submarines,

the Swedish navy had instead been eavesdropping

on the anal alarm calls of Baltic herring.

Now, that's an embarrassing incident for all concerned.

So, misidentifying a shoal of herring

nearly caused an international incident, which is a bit worrying.

But then, sometimes, if you mistake the identity

of another species of animal, you can end up in a world of pain.

Take a look at this weird video that surfaced online.

It shows something very strange.

It's a cat being attacked by a lemming.

But hold on, shouldn't that be the other way round?

Lemmings, like most rodents,

have a reputation for being timid, fearful creatures.

Top of the menu for a host of predators.

So, most lemmings have the sense to hide from everything.

So, just what was going on here?

Why was this lemming behaving so out of character?

Weirdly, zoologist Nick Crumpton

doesn't think it's acting out of character at all.

Ha! Wow, that is very, very brave.

He thinks the clue to this weird behaviour

lies in the lemming's appearance.

Usually, small mammals are quite dull.

They are brown or grey and that's what the American,

the common lemmings, look like.

But the lemming in this video is brightly coloured and stripy,

and that tells Nick that it isn't a common lemming.

This is its Norwegian cousin.

Those black lines and those very light colourations

on the Norwegian lemming's coat tells us something interesting.

It says that, rather than hiding from their predators,

they are actually advertising themselves.

They are very clear to see,

especially when the ground is covered in snow.

It's something we see a lot in nature,

bright colours being used to warn off predators,

and it's known as aposematic colouration.

You see it in insects when they advertise their stings and bites.

In amphibians, warning of their toxic skin.

Even in other mammals, like stinky skunks.

And the fact that this lemming is so brightly coloured

tells you something about its temperament.

Norwegian lemmings are different to other lemmings

and other voles in that they are very, very aggressive.

LEMMING SNARLS ANGRILY

Like the Vikings, these Nordic inhabitants

are bloodthirsty, hairy berserkers.

Norwegian lemmings have been known to kill weasels and fight off skuas.

In fact, the Norwegian lemming will take on perceived predators

of almost any size, including us.

It looks like this cat picked on the wrong type of lemming.

Yeah, my money is on the lemming.

From fishy oil slicks to flatulent herring,

the world is a weird place.

But, whatever you do, don't pick a fight with the wrong lemming!

Right, next up, we go from some oddly aligned animals

to some truly astonishing supersonic sensory abilities.

So, let's start with some cows.

Yeah, cows.

Not an animal normally associated with the weird.

I mean, they're a bit odd looking, but they're not that strange.

So, why, in 2008, were a bunch of scientists really, really excited

about a group of - and I really shouldn't say this - boring bovines?

Well, just like so many good, weird mysteries,

this one started up with some really grainy satellite images.

And they showed something rather odd.

All the cows in a field were facing exactly the same way.

And not just in one paddock.

We looked for pastures all over the world, in all continents

and we randomly selected more than 300 pastures.

So we used satellite images

and, yeah, found a strong preference for the north-south direction.

Sabine and her team had discovered a bizarre bovine pattern

stretching across the globe.

So, what was going on here?

Why would hundreds of herds of heifers all prefer

to face in exactly same direction?

It might be the ancestors of the cattle migrated long distances

and that is still in the cattle and another hypothesis

is that cattle use it as a common escape direction

so if a predator is approaching, it would be a mess

if all the cattle are lying in random order and crash into each other.

But how were they doing it? Sabine wasn't sure.

Some animals navigate using the sun or the stars

and a few can even use their sense of smell to home, but cows -

they're not known for their keen eyesight

or known for their sense of smell.

Sabine was stumped.

That was until she stumbled upon another clue in the images.

Under high-voltage power lines, the cattle are in random order

so they are not aligned in the north-south direction,

but their body orientation is in all directions.

So the power lines were throwing out the cows' alignment,

but there's one thing

that goes hand-in-hand with electricity, isn't there?

Magnetism.

Magnets have two poles - north and south.

Lines of magnetic force radiate out from pole to pole.

But these magnetic fields aren't just flat, in 2D.

Using magnetic fluid, tiny particles of iron suspended in oil...

..you can see those fields radiating out in three-dimensional space.

And one of the largest magnets we know of is the one were standing on.

So you can think of the Earth magnetic field

like a huge bar magnet,

where the field lines go out at the southern hemisphere,

go around in invisible lines all over the world

and re-enter the Earth at the northern hemisphere.

And it is invisible to us,

but many animals can sense the Earth's magnetic field.

And Sabine thinks that cows may be one of them.

So the high-voltage power lines obviously disturbed

the magnetic sense of the cattle so that they are in random order.

So if these cows had a sort of hidden sixth sense,

what Sabine was wondering was, did other animals too?

Perhaps ones closer to home.

She thinks that dogs have a similar secret, but it's well hidden.

In fact, they only give it away at a very specific moment.

I would say, on average, about twice a day.

How you ever noticed your dog spinning around

before they stop to do their business?

What are they doing?

Well, it turns out that dogs are picky poopers.

After studying nearly 2,000 squats, Sabine had discovered a pattern.

So they like to defecate facing in the same direction.

Rover, Fido, certainly my poodles Itchy and Scratchy,

they know their magnetic north from their magnetic south.

Sabine has discovered that dogs, like cows,

can sense magnetic fields.

They poo facing north.

But they don't show this behaviour all the time.

Some days and walks, the dogs were aligned perfectly

and on other days, they were doing it in a random direction.

It seems that sometimes they get distracted, but not by squirrels.

It turned out that, on some of these days, there were solar flares,

magnetic storms.

The dogs are very sensitive to slight changes

of the Earth's magnetic field.

That squatting must be pretty sensitive

to be disrupted by sunshine and the reason they do it is even stranger.

Weirdly, the key lies in the fact that dogs usually only spin

when they're somewhere unfamiliar.

So, if the dogs have not been in that territory before,

they start to establish a mental map by aligning themselves

with the magnetic field lines and using that

if they return to this place later on.

So it turns out that dogs might not just be man's best friend,

they might also be master map makers, too.

You see, when they're spinning,

they're looking at visual landmarks, like these mountaintops here,

and they're using those to calibrate their internal compass.

And once they've done that, they then put down

one of their stinky Xs on the ground.

In fact, though, they don't just put one down.

They put lots down and this enables them

to produce an accurately orientated,

internal mental map of their environment

so the next time they come back,

they can see - or probably SMELL - exactly where they are.

So perhaps the next time you go for a stroll in the countryside,

you should take your bearings from the cows

or even let your dogs take the lead.

They probably have a better sense of where to go

and which direction to go in.

Now, I'm not one to brag, I'm not that sort of bloke,

but I've got to say that my sense of direction is pretty good.

I've got lost twice in my life - curiously,

both times in the same place. And therefore,

I have to consider myself as lucky, because some people

can't even follow a satellite navigation machine.

But could there be a weird reason

why some people's sense of direction is so much better than others?

You'd never believe it if I told you,

but there are intriguing hints

that some of us might have a sixth sense too.

In humans, we do not know if we can sense magnetic fields.

Some people say they can, some people obviously can't.

So, currently, there are two possible mechanisms that are currently debated

and the research is for animals, how they might sense this magnetic field.

So on the one hand, we have magnetite and on the other hand,

we have a chemical cryptochrome-based system.

The really weird thing is that we have both of these

magnetism-sensing compounds in our bodies.

Magnetite is a special iron compound found in certain cells

in an animal's nose or beak.

It acts like a tiny compass, spinning to face magnetic north.

Cryptochrome is a light-sensitive chemical found in animals' eyes.

It also reacts to magnetism and we think it might allow

some animals, like birds, to actually see magnetic fields.

The jury is out whether humans can use these receptors

like other animals do, but we certainly have them.

We have magnetite in our bones.

It was found in bones of the nose and the brain.

We also have cryptochrome in our eyes.

Weirder still, the compounds are actually functional.

If you replace the cryptochrome in the eye of a fly

with the cryptochrome from a human's eyes, it works

and the fly can sense magnetism,

proving that our own magnetic compounds actually function,

although we may - or may not - be able to use them.

So, the next time you're lost, turn off the GPS

and follow your natural instincts all the way home.

You never know, you might actually get there.

Now, even if we can't sense the Earth's magnetic field,

there are some people who have extraordinary animal abilities.

This is Daniel Kish...

..and he is totally blind.

I lost my first eye at the age of seven months

and the second at 13 months from retinoblastoma.

I have no recollection of ever having seen.

I got my first bicycle when I was six.

I go hiking alone, I've travelled to nearly 40 countries,

mostly on my own.

So, how does Daniel manage to do all these things

with such apparent ease?

I tend to think of challenges as puzzles,

as opportunities for discovery.

The clue to Daniel's incredible abilities lies in his nickname.

I seem to be known the world over as the real-life Batman.

No, Daniel isn't a superhero, but, weirdly,

he does share something in common with actual bats.

I am a man who uses the techniques of a bat to navigate.

That's right - Daniel has actually learned to echolocate,

just like a bat.

And he does it with a single sound.

HE CLICKS WITH HIS TONGUE

So, I learned at a very early age that when I click my tongue...

HE CLICKS WITH HIS TONGUE

..I get feedback from the environment all around me.

But how can sound be used to navigate?

Now, sound travels through air,

a bit like the way ripples travel through water.

So, if I make a single sharp sound in this pool, just watch the waves.

The waves spread out into the pool

and then bounce back from the rim in a uniform way to their source.

But let's put an object in that environment,

something big and hard like this.

When the waves hit the object,

they reflect back sooner than the waves hitting the rim

so that when they reach their source, they sound different.

A skilful listener can locate objects

by the way that sounds are reflected differently.

HE CLICKS WITH HIS TONGUE

Here we've got a stairway.

And Daniel is a very good listener.

So we have a structure here that has a roof.

He's never been to this park before,

but he can quickly determine its layout.

A pavilion.

And it's got places to sit underneath

and the roof is held up by poles.

Here's a pole.

So this park has lots of trees and pavilions,

although you have a building on the far side, but it's pretty open.

Daniel doesn't see the world in the same way we do.

You can think of it as a kind of fuzzy geometry.

It does not have the degree of definition

that is available to vision.

But, incredibly, he can still make out textures.

This tree is a total oddball in terms of its shape.

So it starts out quite low here

and then, as you approach it,

it quickly comes up, but it doesn't ever get very tall.

And it's a highly irregular kind of structure here,

it kind of swings out a little bit and then it curves around.

Daniel's abilities are so remarkable

that it drove one scientist to find out more.

Daniel is not only exceptionally good at echolocation,

he's also exceptionally good at verbalising how he does it.

Having Daniel here around

is like almost being able to talk to a bat.

To find out what's happening inside Daniel's brain

whilst he's echolocating, Lutz is conducting a series of MRI scans.

Inside the scanner, Daniel is listening to virtual echoes

and Lutz is watching how his brain reacts.

The results are astonishing.

He can really see with his ears

and it's not only that he can process spatial information

acquired with his auditory system,

but he can also recruit parts of his visual cortex to do this task.

Put simply, Daniel is using the part of his brain

that would normally deal with sight

to help process sound into spatial images.

But here's the truly weird thing -

the scans also show there is nothing unique about Daniel's brain.

If one part of the brain has really no input any more

because of a sensory deprivation,

then this part can be taken over by other modalities.

In essence, our brains are flexible.

They can adapt to meet new challenges

in the most incredible ways.

Daniel has recruited part of his unused visual system

to improve his echolocation.

Anyone can improve their ability to echolocate.

So, with some dedicated practice, even you could learn to do it.

But before you try riding your bike blindfolded,

perhaps practise your skills at home first?

From oddly aligned ungulates

to dogs that will only poo facing north,

our world is full of hidden oddities.

We may or may not have a sixth sense, but with practice,

we can train ourselves to see with our ears.

Next, to get from some very fancy fairy rings

to some very mucky gold,

we have to take a trip to the other side of the world.

One of the world's weirdest landscapes is in Namibia.

A vast scrubland, pockmarked with thousands of shallow circles.

Rings of grass surrounding barren soil, about five metres across.

One local myth holds that these rings are the footprints of gods.

But it's not just the locals that were intrigued by these rings.

So the interesting thing about the Namibian rings,

they don't have any human origin to them.

They extend over such a vast area.

You can travel hundreds of kilometres

and you'll find exactly the same patterns.

So what's causing these elliptical oddities?

Well, generally, if you've got a weird mystery,

you've got some pretty weird theories to go with it.

Over the years, there's been many scientists

who've seen the fairy rings

and puzzled over what might have been causing them.

Some of the earlier ideas suggested

that maybe there was gas seeping from underground

or perhaps they were the remnants of toxic bushes

that had previously lived there and had poisoned the soil

and then nothing could live around them any more.

But that's not all. Some scientists thought

that radioactivity could be causing the circles.

Others favoured fungi.

Some even thought they might be made by rutting ostriches.

So, which of these odd theories

was the correct answer to this circular conundrum?

As it turned out, actually, none of them.

You see, when the scientists got down on the ground,

inside the fairy rings, they found...

Well, not much.

Each ring was formed from a patch of bare earth

surrounded by some tall grasses.

Inside were no gases, no toxic plants, no radioactivity,

no fungi and absolutely no ostriches.

But they did find something else.

Every one of the fairy rings is colonised by ants and termites

and there are nests around the edges of the rings.

Were these hive-minded harvesters the real cause of the fairy rings?

There are other parts of the world

where leafcutter ants clear patches of vegetation

and leave bare ground

or where termites clear the areas around their nests.

Well, it looked promising and termites are master architects,

building complex mound structures all around Africa.

They certainly seemed like the perfect fit,

but there was a problem.

Understanding how you get cleared patches,

that's relatively simple.

But understanding how you get these patches to be spaced regularly,

that's the really tricky part.

Ants and termites don't clear perfect circles

and, even if they did, it's unlikely that they'd be the same diameter

and the same distance apart.

They'd have to be pretty obsessively compulsive colonies

to achieve that. The termite theory? No. It's another dud.

One scientist believed that the answer

lay in a change of perspective.

None of these different researchers has so far found an ultimate answer.

So I thought that we should maybe not only look at fieldwork,

but we should also look at remote sensing applications

and area images.

Stephan realised that everyone was looking

at what caused individual rings

and not what had caused the large-scale pattern.

It's a bit like looking at a pimple

and trying to describe a whole disease.

Fairy circles, if you look at those in area images,

they have clearly a very distinct pattern.

It's actually a very, very unique pattern.

After studying thousands of fairy rings from above,

Stephan realised that the rings were roughly the same size

and the same distance apart.

But critically, they were only ever found in very specific areas.

The fairy circles typically occur in the transition

from very arid grassland to desert,

so we believe that gaps emerged due to competition for moisture.

Yes!

He realised that the fairy rings only form

with exactly the right amount of rain.

Any more water and they would simply be grassland savanna.

Any less and it would all be desert.

And this realisation led Stephan to a truly weird conclusion.

What we now think

is that fairy circles are actually creating themselves.

The fairy rings develop as a way for the plants

to organise themselves, to survive in an area with very limited water.

Imagine this coin is one of those fairy rings

growing out in Namibia.

The long grasses that grow around the edge of the rim here

are competing for scarce water.

Their roots are radiating inwards, taking away all that water

so it's barren inside the ring there.

Now, other plants want their share of those resources too,

so they start to pack themselves in.

Unfortunately, this means there is a problem

because the long grasses on the outside of each rim

are buzzing right up against one another.

Plants don't like that.

They want to avoid competition,

so what they do is they space themselves out equally like this

and what we see is this regular pattern,

which is so typical of the vegetation in this area.

It's a weirdly elegant solution,

requiring no termites, no gods and absolutely no ostriches.

So the fairy circles of Namibia

may be a bit more mathematical than magical,

but down in the jungles of South America,

explorers recently discovered another ring-based riddle.

Found in Peru,

pictures of this weird structure first surfaced in 2013.

When they hit the web, they went viral.

These things were just fascinatingly weird.

The structure of it, it's like a white picket fence around there

and then the pole in the middle,

there's nothing else in biology that looks like this.

This miniature marvel sparked a furious debate across the net.

People had a lot of ideas

and they figured it was something very small making this.

Nobody was quite sure

and actually some experts out there said it was probably a hoax.

They didn't believe anybody had found these things.

Phil knew he needed to see them first-hand to find out more.

Armed with the information

detailing where those first photographs were taken,

Phil and his team set off into the jungle

to solve this Peruvian puzzler.

So, to solve this thing,

I got together some of my best entomologists

and we went down to Peru and to get there,

it took us three plane rides, a bus ride and then two days of canoeing

up the Tambopata River to get to the Tambopata Research Center.

Then, every single night for about two weeks,

we took these canoes out to the island

where the structures were found

and we were just really hoping to find a single one.

We had no idea if we would find any of them at all.

Working at night and using torches

to try and cast shadows of these tiny structures,

they soon discovered that finding a hidden henge

is a lot harder than it looks.

We looked up and down trees, looked in the bushes,

looked in the same places that these things were found before,

hoping to find a single one because as of then,

only two had ever been seen, ever.

When you look at them, they're about that big in diameter

so this is a very small structure in a very big rainforest.

We had no idea if we would even see a single one.

After weeks of hard graft, their efforts finally paid off.

We looked and we looked and we found one and we were just over the moon.

But they didn't just find one.

Over those two weeks, we ended up finding over 50 of them

in all different conditions.

Some of them looked like they were completely fresh,

others looked like they'd been there maybe a few weeks.

So, Phil and his team had proved that these Amazonian oddities

were the real deal, not some elaborate internet hoax,

but they still didn't know exactly what was making them.

We thought maybe it was a fungus that was growing on these in a circle.

Then they found one of the structures on a plastic tarpaulin.

Normally, when you see a fungus, the part that you actually see

is just the tip of the iceberg of the organism.

Underneath, there's all these little veins called mycelium.

And mycelium can't grow through plastic

and the underside of the tarp was clean,

so the structure couldn't have been made of fungus.

Instead, it looked like it was made from silk.

Incredible? Certainly, but not altogether very helpful.

You see, in the jungle, there are quite literally thousands,

perhaps tens of thousands, of silky suspects.

Some moths create intricate cocoons from silk when they pupate.

Spiders spin complex webs and egg sacs with their silk.

And lacewings, well, they lay eggs on top of delicate silk stalks,

but to find out whodunnit,

the team first had to establish what these structures really were.

We put them under a microscope and cut into them

and, when we looked inside, it look pretty much like an egg.

So, inside the base of the central spire was an egg, not a pupae.

That ruled out moths, leaving just spiders

and lacewings as the mystery silk spinners.

To unmask which was the evasive egg maker, they put a few

of the structures into sealed jars in the lab and then simply waited.

So, finally, after a few days,

we saw a tiny, tiny thing crawling in one of those jars and it was tiny

and it was red and we weren't sure what it was,

but we got out the super macro lenses so we could see very close

and we realised that it was a tiny spider.

We found a spider that does all this work,

builds this beautiful thing, just to lay one egg in there.

It's an amazing amount of work for an arachnid to do

for the sake of just a single egg!

You see, typically, they'll lay tens,

if not hundreds, inside their silky sacs,

so the effort that this species is going to

might yet prove to be even more incredible.

Phil thinks that the circular fence around the egg spire

might actually be like a fence to keep predators out.

And perhaps to keep prey IN, too.

That fence surrounding it is a trap for tiny mites

because we kept finding them with mites stuck inside,

these tiny, tiny things that would be perfect prey size

for a newly hatched spider.

If that were the case,

that would make this even more truly one-of-a-kind.

As to which super spider species created the silky structure,

Phil isn't sure, as they've yet to managed to raise one to adult stage.

But he's already planning a return trip

to hunt down the proud parents.

We've got maybe 1% of it solved. There is 99% to go.

So, strange spiders are producing beautiful rings

to protect their families.

But then we like to put rings on the fingers of our loved ones, don't we?

Although it's my duty tell you that at some stage

in the pretty new future, the gold that is used to make them

might come from a less romantic source than you'd ever imagine.

There's an old saying - where there's muck, there's money.

And it's something that farmers have known for centuries,

liberally spreading muck on the fields

and turning it back into food to sell in our supermarkets.

Now, I've noticed that recently

a lot of muck has been hitting the headlines

and not just in the tabloids, either,

because apparently it's the new wonder material.

Scientists have recently worked out how to turn solid waste

into pure drinkable water.

They've even managed to collect the gases it gives off

and use them to power our transport, too.

So now, you can hop on the number two from Bristol to Bath,

fuelled by our number twos.

But, despite all this, one scientist currently thinks

that we are missing out on our waste's greatest potential.

We are interested in what goes down the drain.

Everyone in society gets rid of things down the drain every day.

They are all flushing away millions of dollars.

So, Paul has come up with one of the weirdest get-rich-quick schemes

ever invented and, like all such schemes, it involves gold.

We thought we could go out and prospect for gold

and silver in unique places

and it turns out one of these unique places

to prospect for gold and silver is poo.

Yes! You heard him, you heard him correctly!

Paul wants to get precious metals from poo.

He's not an alchemist, but, amazingly,

he may be onto something here.

There are some truly weird ways

that precious metals can find their way into our waste,

some more obvious than others.

We can find precious metals in everyday items,

like our make-up, toothpaste and toiletries.

Manufacturers sometimes put silver particles in our clothing,

like socks, to reduce odours.

They even put things like titanium in our foods to keep them fresh.

And it's not just household waste that ends up in sewage plants.

Mineral-rich run-offs from farms and industry

find their way here, too.

We took pictures of the waste water solids

using high-powered microscopes

and we find little particles of gold and silver

in what are called sewage sludges at waste water treatment plants.

And when you concentrate the sewerage sludge from entire cities,

the results are eye-watering.

Quite literally eye-watering.

For a city of one million people, every year,

there's about 13 million worth of precious metals

and most of that value is actually in gold and silver.

Now, gold is a lot, lot, rarer than you'd think.

It's very difficult to mine,

it's very expensive to get out of the ground indeed

and that, in turn, makes it incredibly valuable.

The amount of gold in the solids

coming out of these waste water treatment plants

is about the same as what mining companies will blow up mountains for

in terms of the amount of gold content of rock

that they'll go and mine, it's the same ore content.

And rather than saving this mineral-rich muck,

we're currently just dumping it.

Every day, there's dump trucks

that leave waste water treatment plants carrying biosolids.

They bring it to landfills

or they burn it or they spread it out on the land

so each of those dump trucks contain more than enough gold

to make a gold ring.

That's an awful lot of gold

and Paul is working on ways to reclaim his grubby gold for good.

He's been looking at other places where they are experimenting

with extracting gold from waste, like the Suwa facility in Japan.

But to get their gold, they've been crudely burning their waste.

Paul's working to find a more efficient

and more environmentally friendly solution to this mucky problem.

It's a weird world where magical rings

turn out to be mathematical oddities,

spiders makes surprising silk henges

and we all flush away a fortune in gold.

OK, some of that was pretty strange, a little bit freaky,

but I've got to tell you -

we've only just touched down on Planet Weird.

There's a lot more to come.

Next time, what caused gigantic hailstones on a sunny summer's day?

And how could a pop band change the way that music is made forever?

If we sell one little vial of our new album as DNA,

we will have sold trillions and trillions of copies.

Why does this man get legless without drinking any alcohol?

Have you had anything to drink?

Nothing.

And finally, how can a volcano glow bizarrely blue?