Original subtitles

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

Argh!

..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.

..monkeys with first-aid skills...

I sent it to my family.

I sent it to my friends, said, "Have you seen this?

..and the unexplained.

An unborn twin discovered inside a brain.

There was multiple hair follicles, bone and teeth.

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

Argh!

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 find the answers to some of the natural world's weirdest questions.

What's causing these rocks to spontaneously explode?

Why are bats' brains being removed in a cave in Hungary?

What on earth are these strange green balls?

And why are these cats wearing bibs?

Deserts. Miles and miles of sand.

But add in the power of a storm...

..and the result is not exactly a marriage made in heaven.

Phoenix, Arizona.

Something strange is building out in the desert.

Winds are strengthening.

This is certainly not a nice day for a white wedding.

ORGAN PLAYS "Here Comes The Bride"

The day of the wedding itself was relatively calm.

The weather itself was really great. It was bright and sunny.

It was the big day

for one happy couple.

We came to the venue to get dressed, take pictures.

Friends and family were still kind of arriving.

Everything was going smoothly.

It was a day they would never forget.

Their dream wedding. Something they'd been planning for months.

I'm standing at the altar looking for the future bride,

future wife, coming in.

That was an awesome sight to see.

What could possibly go wrong?

We're here this afternoon to share with Gustavo and Jennifer

a most important moment in their lives.

A good, solid ten minutes in, everything was going fine.

And then, I remember looking at Jenny, and I remember looking up.

My jaw dropped. My eyes got big.

I look at Jenny, Jenny's looking at me with this scared face.

I couldn't help it. I had to turn around to look.

"What is he looking at?"

What they saw was an immense wall of dust coming straight towards them.

We just...pretty much just hold on tight!

Hurtling towards them was an immense cloud of sand,

a super-sized dust storm,

a bizarre phenomenon with an even stranger name -

haboob.

Haboobs are amazing, because they're like this impending doom.

It's just kind of this wall

that is getting closer,

like something apocalyptic, something incredible is happening

and you're just standing there watching it

and there's nothing you can do about it.

Haboobs are a desert phenomenon, but they are no ordinary dust storm.

It's this towering, churning wall of lifted sand and dust

that sets them apart.

But what starts them off?

Haboobs are formed by thunderstorms.

Out here, at least, when thunderstorms form,

they just drop the rain straight out the bottom.

Haboobs usually happen during the rainy season

in Arizona between June and September,

when thunderstorms can be particularly heavy.

These thunderstorms create strong downdraughts of cold air,

which hit the dry desert floor and spread out,

kicking the dust up high into the air, creating an imposing wall.

It's almost like a bomb exploded.

The dust will start rolling away from the storm,

and then, a lot of times, that air that's thrown out

will actually kick up more storms above it

and those storms will build up and they'll drop downdraughts as well.

They kind of end up creating this huge wall of dust.

So, pretty quickly, a few grains of sand

can be whipped up into a swirling, spiralling wall of dust,

sweeping across the desert floor,

engulfing everything in its way.

Haboobs can be massive.

The biggest ones that I've seen have been a mile tall

and 100 miles wide, and have winds packing around 60mph.

Once the haboob hits,

visibility can be reduced to near zero in a couple of minutes.

Planes have to be grounded. There are huge pile-ups on the roads.

'Let's look at the freeway. The freeway has backed up.

'It looks like there's an accident over there right now.'

The high winds tear down trees and pylons...

..and the whipping dust gets everywhere.

You don't usually get a lot of warning

that a dust storm's coming in,

so they can spring out of nowhere.

Meanwhile, back at the wedding,

things were beginning to take a turn for the weird,

as the winds strengthened and the bridal party was blasted with sand.

And as if there wasn't already enough dust blowing around,

Jenny and Gus still had the sand ceremony to do.

We each have a different colour sand and we pour it into a vase,

so it creates kind of a swirl as you're pouring it into your vase,

to symbolise the unity of both of us coming together as one.

They represent all that you are and all that you will ever be

as individuals.

As we were pouring, we were getting pelted with sand left and right.

My husband here is just, "Let's just stop this.

"We don't need it. This is ridiculous right now."

And of course, me being the bride and this is what I want,

"We're going to continue to pour sand until we are done!"

And so we got most of it in there,

then, finally, even I had to concede we needed to stop.

I'm going to make this quick, OK?

We should just end it and just get out of here.

I can't see them, I can't see us.

Sure enough, the judge kind of skipped a lot of things

and went to, "I pronounce you husband and wife," and we kissed.

I present you, Mr and Mrs Gustavo Luna.

You know, we look back at it now, and kind of laugh at it.

- Cos it's nobody's fault. - Yeah.

- Definitely nobody's fault. - We can't control the weather.

CONGREGATION CHEERS

Surely one of the weirdest weddings ever witnessed!

I think it's safe to assume

that no-one is going to forget that wedding in a hurry.

But you know, in this weird, weird world,

it's not just important events that we try to preserve for all eternity.

No, some people have gone to extraordinary lengths

to preserve themselves.

A statue of a Buddha in a museum in Budapest.

Surely nothing weird here?

But in fact, this golden statue was hiding a secret.

Whilst it was undergoing restoration,

researchers spotted something peculiar...

..and a CT scan revealed their discovery in full -

an entire body, hidden inside.

It had been covered with gold, to look like a Buddhist statue,

suggesting that the body was most likely that of a Buddhist monk.

But that wasn't the end of the story.

It also appeared that before being placed inside the statue,

the monk had been mummified.

Mummification is the preservation of dead bodies,

so that the...significant amount of the soft tissue is preserved.

Normally, dead bodies decay quite rapidly,

because of bacteria and enzymes,

so mummification really involves processes that stop decay.

We know a lot about mummies through Egyptian mummies, of course -

the iconic mummies, if you like.

Many Egyptian mummies were carefully prepared once the person had died.

The internal organs were removed

and the body would be treated with natron,

a type of salt with fantastic drying properties.

They were then wrapped in hundreds of metres of linen.

It's the drying out that's key.

The lack of water prevents bacteria and enzymes from working,

and this prevents the body from decomposing.

But in the case of the golden statue mummy,

it seems that something astonishing could have been going on.

When you find a mummy like this,

with that strong Buddhist connection,

it's actually quite likely

that there was self-mummification involved in this.

It might just be that, in this case,

the monk actually started to mummify himself whilst he was still alive.

Self-mummification took place in countries like Japan and China

in areas where Buddhism was practised.

It started in about the 12th,

and carried on through to the early 20th century,

and it was a gruesome undertaking.

With this process of self-mummification,

It would be a question of the priest deciding

they wanted to go on this journey, if you like,

and so start by restricting their diet significantly.

By limiting their food and water,

they were beginning to preserve themselves

months, even years, before they actually died...

..and, by surrounding themselves with candles as they meditated,

their bodies would dry out even further.

They might also drink the sap from certain plants to poison themselves

and destroy the bacteria that would decay their body after death.

And it all took place in a tiny room.

They would be in these very confined spaces,

and they would have a bell that they would ring periodically

to let their colleague priest know that they were still alive.

When the bell stopped ringing, the monk had died.

It's thought that by self-mummifying,

the monks were attempting to become semi-divine beings,

choosing to live in an in-between world

between earth and permanent Nirvana,

to help others become fully enlightened

and reach Nirvana themselves.

I think what is interesting about the self-mummifying priests

is that they clearly understood the materials and methods

they were using would actually go some significant way

to preserve them forever, effectively.

What can I say? I suppose it demonstrates commitment,

although that's an understatement of enormous magnitude -

but, over time, people haven't just been keen to mummify themselves -

the ancient Egyptians liked to preserve their animals, too.

They were huge cat fans,

and perhaps, if they were still alive today,

they'd feel very much at home in the American city of Minneapolis.

You see, this isn't a music festival...

or a comedy gig.

No, this is a gathering of people with only one thing on their minds.

You look around and there are all these people who are coming together

to do something unbelievably ridiculous.

This is the Internet Cat Video Festival.

Yeah, we're all going to get together and watch videos of cats,

two-minute videos of cats going like this.

I am excited to see old ones and new ones, and all sorts of cat videos.

Every year, over 10,000 feline obsessives turn up to watch

back-to-back internet cat videos.

It was nice to know that I'm not the only weirdo

who sits on the internet and watches animal videos

to get their animal fix all day.

Cats are undoubtedly big news online.

Last year alone, nearly two million cat videos were posted on YouTube.

And they received a staggering 25 billion views.

But why? Why are cat videos so popular?

Cats have become an internet sensation,

and I think there is probably a couple of reasons for that.

One is that they are very photogenic.

They've got these lovely round furry faces,

which everybody seems to find appealing.

They're rather like baby faces,

because they have the forehead like babies do,

and again, that makes them very appealing to us.

It makes us want to look after them.

The second thing is that their faces are not very expressive,

which you might think is a drawback, but it's not.

When you take a photograph or make a film of a cat,

you can kind of put any connotation, any caption,

you want on it, and it's believable.

What's surprising is that,

whilst there are many more dog than cat owners in the UK,

cat videos are four times more likely to go viral

than those featuring our canine companions.

I've watched a lot of cat videos.

I think the favourite one of mine

is the cat that tries to get into smaller and smaller boxes.

That is a very typical piece of cat behaviour.

Cats love going inside boxes,

because they like the security of a confined space,

particularly if they're feeling a little bit nervous.

This is a cat that has taken that to total extremes.

But, look, whether you're watching the videos in a field

with thousands of likeminded cat addicts, or on your own,

I can't help but feel it's a bit of a waste of time, isn't it?

Well, no. Apparently it's not.

At the Indiana University Media School,

recent research has shown that watching cat videos

seems to increase your sense of emotional well being.

Ha!

I think she's eating it!

Viewers boost their energy and positive emotions,

whilst also feeling less anxious,

annoyed and sad.

And even if you're watching cat videos instead of working,

any guilt you might feel seems to be outweighed by the enjoyment...

..and may even help you to take on tougher tasks afterwards.

But, whilst cats today are some of the biggest stars of the internet,

they're not the first felines to be filmed doing something funny.

The first ever cat film was shot way back in 1894,

at the very dawn of cinema,

with two cats having a boxing match.

The man behind it was none other than Thomas Edison.

But behind the veneer of the cute,

the box surfing, the dog barking,

the millions of adoring fans, I have to tell you,

there is a darker side to our feline friends.

Some of them are crack killers.

Recent estimates suggest that 275 million small animals and birds

are killed in the UK every year by cats.

Most people have a cat, they want it to be a pet,

they want to have a personal relationship with it,

and they don't want the gory little bit of mouse

being deposited on the kitchen floor in the morning.

In Oregon, one such cat owner really had had enough

of getting these grisly little presents each day.

My cats killed birds.

I like wildlife,

and I like the garden,

and they were ruining the whole thing.

I didn't know how to stop them.

I kept them inside, and they really didn't like it.

They had cat fights, they sprayed, I would come home from work

and the place reeked of urine and the cats hated each other.

It was just horrible, trying to keep them inside.

To stop cats from catching birds,

you can get collars complete with bells or sonic deterrents on them,

but sometimes, these don't work.

So, Sue had to think outside the box.

Or not...

I started to think about, if I could build a wall around the cat,

and so I envisioned a cardboard box with a hole cut out.

I think someone's already got that one covered, Sue.

And then it was, "Well, maybe I could just put a piece of cardboard

"in front of them."

Sue started by tying a flap of old boot leather around their necks.

Whether it would work or not, it was worth a try, you know?

So I let her out, and she didn't catch a bird for a week.

And her prototype soon turned into this.

By interfering with the cat's timing and co-ordination,

a study has shown that this bib could stop 80% of cats from killing...

..but then, even if they do manage to catch something,

at least they won't spill anything down their front.

So, from the ultimate wedding crashers

in the arid deserts of Arizona...

Go, go, go!

..to monks drying themselves out

in the hope of achieving immortality...

..thousands of feline fans watching adorable cats on the internet...

..and killer cats wearing bibs -

it really is a weird world out there.

Our next journey takes us from some unexpected explosions

via an albeit tortuous route to some insects in disguise.

Let's head to the golden state of California.

Twain Harte, on the edge of the Sierra Nevada,

is a small holiday town popular with families.

Twain Harte, in the summer,

for us and our family is a getaway, where we go to relax.

It's a place we can leave the city behind

and just have some family time.

It's crowded, the beach is full, there are kids screaming and running

and people walking around and walking their dogs.

But, on the weekend of Twain Harte's annual water carnival,

something was about to happen

that would completely shock this close-knit community.

When I first heard it, I thought it was dynamite going off.

If it had happened a day earlier,

there would have been 350 people out on that rock.

But there was one family on the rock that day.

We decided to go down to the beach because the weather had turned.

I was with my in-laws and my kids and my niece and nephew.

So we were hiking along and decided to go across the dam,

over to the rock.

All of a sudden, it was like a bomb went off.

From the local cafe, the commotion was caught on camera.

HUGE CRASH

PEOPLE SHOUT

The entire rock started to shift and move,

and I actually thought it was an earthquake.

California is no stranger to earthquakes.

They can be completely devastating,

causing billions of dollars' worth of damage.

The San Andreas Fault,

part of a sliding boundary between two of the earth's tectonic plates,

is responsible for much of this seismic activity.

But, back on the rock, Steve was beginning to think

that maybe earthquakes weren't to blame this time.

As we started to realise that it really wasn't an earthquake,

because being from the area we had felt earthquakes

and it was very different...

..a crack appeared from the back of the rock

and it started moving towards us.

Explosions were coming out of the crevice.

It was terrifying for the kids and for us,

because we really didn't know what was going on.

We truly thought that this thing was going to blow.

Over the next couple of weeks,

more explosions occurred on the rock.

Whoa!

The whole area, including the dam, became unsafe.

The lake had to be closed.

Geologists were fascinated by these unusual explosions.

Rocks are like people.

They get stressed and they react to stresses in very different ways.

Rocks can accommodate stress and deal with it,

or, if the stress is strong enough, they break.

The question at Twain Harte, really,

is what actually caused the stress.

Dr Eppes thinks there's not one simple explanation,

but a possible combination of three elements.

As well as being in an earthquake zone,

at the time, California was suffering

one of the most severe droughts on record.

Due to the ongoing drought,

The water table there has been lowering.

This could be causing, or could have caused,

another sort of stress to develop.

The rock at Twain Harte is a granite dome.

As the water table lowered during this drought,

it lightened the load on the dome, allowing it to rise up.

As the dome lifted, the edges were compressed by surrounding rock...

..but there was one final stress to add into the mix.

On the week leading up to August 3rd at Twain Harte,

you had temperatures that were ten degrees above normal.

And then, the day that the rock cracked

was actually ten degrees below normal.

Dr Eppes believes that the rock cracked on this exact day

because of simple expansion and contraction

under huge temperature swings.

It was the straw that broke the camel's back.

The pressure builds and the rock cracks open explosively

to relieve that pressure.

It's called exfoliation, where the outer layers of the rock split,

like peeling the rings off an onion.

But the damage, the chaos caused at Twain Harte by that exfoliation,

was nothing compared to what happens if you add in much larger rocks,

and the forces of gravity.

Just up the road at Yosemite National Park,

the effect can be breathtaking.

These rocks may crack at any time, without warning.

A rockfall, look!

Look at that piece!

They may look small,

but in fact, some are bigger than a double-decker bus...

..and, in an area with four million visitors a year,

this is one weird force of nature that has to be reckoned with.

But the danger of exploding rocks won't put some people off

from returning to Twain Harte.

We'll never stop coming back to Twain Harte.

We're going there this weekend

and hopefully we'll see the lake filling up

and we'll get ready to get out on that rock.

It's a dangerous world out there,

there's no doubt about it,

but sometimes the threats come from where you'd least expect it.

I saw the shadow come up on my left-hand side and go past me.

I just stopped dead in my tracks and I could feel this intense pain...

..as if you were being stabbed by hundreds of syringes.

The lower part of my ear felt like it was on fire.

It was a pain that I had never felt before.

Tom Hart Dyke is a plant hunter

who's travelled all over the world

in his search for the weird and wonderful.

He's used to putting himself in some pretty testing situations...

..and an expedition to the tropical rainforest

of Queensland in Australia was no exception.

The conditions on the expedition were pretty tough.

I was on my own, seeing plants in the wild.

On the forest floor, it is very dark.

You can hardly see where you're walking

and you're always pushing away foliage of various sorts.

I just stopped dead in my tracks

and I could just feel

this extraordinary, intense throbbing pain.

Now, Australia is renowned for its long list of dangerous wildlife.

Where Tom was walking there were funnel-web spiders

and brown tree snakes capable of inflicting a nasty wound

on the unsuspecting.

Initially, I assumed it was a massive hornet

or some insect that had stung me.

It was unbelievable, intense throbbing pain.

Tom had stumbled across something he'd heard about

but never actually experienced before.

It was the gympie gympie plant,

otherwise known as the deadly stinger.

The deadly stinger is known as the world's most dangerous plans.

It's a very unassuming plant that you wouldn't know, particularly,

was that poisonous.

When you look at it, it's not that interesting.

The berries are quite nice, the leaves have quite nice shapes,

but it's not a plant that certainly stands out.

Gympie gympie means stinging tree or bush,

and it belongs to the same family

as the familiar stinging nettle in the UK.

But, whilst nettles can hurt,

it's nothing in comparison to the agony inflicted by the gympie gympie.

The sting is extraordinary painful.

Depending how much you get stung,

it can cause your immune system to just shut down.

When you're stung by the deadly stinger, you never forget it.

Months after you've been stung, the pain can come back.

There's no other plant in the world

that causes as much re-occurring pain as the deadly stinger.

Small red spots can appear

and form a larger swollen area.

Pain may spread to other parts of the body

like the head, limbs or armpits,

lasting for days.

And the cause of all of this pain

can be seen with a closer look at the surface of the leaves.

They are covered in tiny silica-tipped hairs,

as many as 15,000 on each side of a single leaf.

Each hair is like a hollow hypodermic needle.

As you just lightly brush past it,

there's a round circular bubble at the apex of each particular hair

that breaks off and this then penetrates into your skin

releasing a concoction of acid.

The top bit of the needle or the whole part

can break off into the skin so it remains in there.

That's what causes the reoccurring pain.

I've heard stories of it recurring for up to two and a half years

after the initial sting.

But it gets worse.

These plants have been known to kill dogs, kill horses,

even lead to the deaths of humans.

In World War II, an Australian serviceman was stung

during his military training.

He then spent the next three weeks tied to a hospital bed

because the pain was so intense.

There's a story, and it may be just a story,

that an officer mistakenly used one of the leaves as toilet paper

and then shot himself because he couldn't take the pain.

The actual chemicals in the plant are not fully understood,

but it seems like a cocktail of compounds are involved -

and they're so stable that, even in dried specimens

where the leaves are more than 100 years old,

the hairs can still give a horrendous sting.

But the gympie gympie is not invincible.

Sometimes, the entire shrub is stripped overnight

leaving just a chewed-up stem...

..but which species could possibly eat a plant

covered in such toxic spines?

The hardy culprit was a shy, rather harmless-looking rainforest wallaby

with an equally odd name -

the red-legged pademelon.

It usually lives alone, feeding on fallen leaves on the forest floor

and berries and fruits from shrubs,

but it can eat the gympie gympie as well,

and seems simply to have adapted to deal with the sting over time...

..and it's not the only one.

A number of species, like this green ringtail possum,

can eat the plant -

but they're all native to Australia.

And you might think that the excruciating pain

Tom Hart Dyke suffered in the Queensland forest

would mean he'd never want to see a gympie gympie again -

but he's actually brought one of them back home

where it has pride of place in his collection.

But don't worry,

it's highly doubtful that the gympie gympie

would ever grow wild in the UK.

It's a tropical plant,

so it would be unlikely to survive outside of Tom's greenhouse.

But you don't always need spines filled full of vicious toxins

to deter predators. Oh, no.

Some species have evolved far less deadly ways

to avoid being on the menu.

This is Papilio dardanus,

the African mocker swallowtail -

and, although it may not look like it,

it's been described as the most interesting butterfly in the world.

For 100 years, collectors only ever found males -

which is clearly a bit weird -

and, whilst these collectors were trying to work out

why they only ever found male mocker swallowtails,

they came across other strange butterfly conundrums.

What was equally strange was that, for some of these species,

they only ever found females.

No males.

It was a complete mystery.

So what on earth was going on?

Well, to get to the bottom of this mystery,

scientists took some eggs from one of the female butterflies.

When the scientists first bred out the butterflies

from a batch of eggs,

they assumed that there'd be

just the one female type and one male type.

In some species of butterfly,

the males and females look very different.

In others, they look pretty much the same.

Either way, there's usually only one form of the male

and one form of the female,

but when the African mocker swallowtails

emerged from their pupae,

those scientists discovered something astonishing.

They were surprised to find

that there were several different-coloured female forms

in the same batch.

So, whilst the males all looked the same,

the females were a whole range of colours and shapes.

At last, the collectors had an answer to the mystery.

All of these different-looking butterflies

are actually the same species.

So why did the females come in such a huge variety of colour and design?

The answer lay in self-defence.

Some species use camouflage to hide themselves from predators.

Others taste toxic and are brightly coloured to let predators know that.

If a young bird eats a distasteful butterfly,

it learns very quickly that that butterfly is not nice

and tends to avoid that colour of butterfly for the rest of its life.

And the female African mocker swallowtail

has an incredible twist on this tactic.

The female mocker swallowtail has developed different colour forms

to match these different poisonous butterflies

so they don't get predated so much.

Ingenious.

It's an extraordinary adaptation.

Up to a dozen or more different forms of the female

have been discovered so far.

Although the mocker swallowtail isn't poisonous,

they've evolved to look like other species which are.

OK, but there's one last thing that doesn't seem to make sense.

I mean, how does a male African mocker swallowtail

find a female African mocker swallowtail

if those females look like a great range of other butterflies species?

The males look for females of the same species -

first by visual cues,

but closer to, they use their antennae to sniff them out

and they use pheromones to make sure it's the right

species of female before they can mate with them.

The males can sometimes mistake other butterflies for the female,

but I've never seen one mate with the wrong species.

So this mimicry is a brilliant solution

to the problem of avoiding predators,

and it's allowed the African Mocker Swallowtail

to become extremely successful.

So, exploding rocks in a sleepy holiday town gave tourists

a nasty surprise...

..whilst one unsuspecting traveller

got a sharp shock from a plant with a spiky form of self-defence...

..and there's an insect which protects itself

with some incredible impersonations.

All extraordinary goings-on in our strange world.

Finally, we start with a monstrous headache

and end up in a bizarre alien landscape full of green blobs.

Yamini Karanam was born in Hyderabad in India in 1988.

At the age of 25,

she came to the University of Indiana to study for a PhD...

..and that's when things started to turn a little bit strange.

For more than six months,

I just didn't know what it was like to not have a headache.

I would wake up with a headache

and I would have headaches through the day,

and I would have headaches through the night.

Yamini's life was on hold.

She had to stop her studies for several months

until her quest for medical advice led her to a leading surgeon

at the Skull Base Institute in California.

When Yamini first came to see me,

her symptoms were - first, headaches, second, fatigue.

I would sleep for more than 10-15 hours a day

and still wake up very, very drowsy.

What was more concerning to me

were another set of symptoms that were cognitive symptoms.

She's a 26-year-old PhD candidate,

so she's a fairly intelligent human being,

and she reported that she could not understand what she was reading.

It went from "I'm not sure what I understand from this text"

to, "Oh, my God! My head is in the clouds

"after reading a couple of lines!"

And that if she was in a room full of people,

she could not comprehend the conversation.

An MRI scan revealed a worrying lump right in the middle of her brain.

My biggest fear was that this was a malignant,

what we refer to as a cancerous, brain tumour.

We had to do something because she was literally dying.

Dr Shahinian specialises in pioneering keyhole surgery

at the base of the skull.

We can see this is the upper brain and this is the lower brain,

and between the two, there is a natural space that you can see.

So we access this space, the natural space,

through a tiny opening here, a keyhole approach,

and use an endoscope to go between the upper brain

and the lower brain and access this tumour that way.

But during the surgery, when he saw the exterior of the tumour,

his worst fears appeared to be confirmed.

The tumour surface was extremely gritty and hard,

and normally that is a bad sign,

because malignant tumours can be that way.

But when he looked inside the tumour,

what Dr Shahinian discovered left him truly astonished.

There was multiple hair follicles, bone and teeth inside the tumour.

It wasn't cancer -

but what was this bony, hairy, toothy lump inside her head?

It was a bizarre benign growth known as a teratoma.

Teratoma comes from the Greek word "monstrous tumour"

because, over the ages,

we have known that these tumours

can have all kinds of structures in them - sometimes hair,

sometimes teeth, sometimes bone, sometimes eyes, sometimes limbs.

And the teratoma had been with her much longer than she'd realised.

They told me that I was born with it,

and it's been growing for the past 26 years.

So Yamini's teratoma had always been there,

but it was only in recent times that it had created problems -

but then, the causes of these teratomas in the first place

is something that's been disputed and debated in medical circles for years.

There are two competing theories.

One theory is this is just an embryologic accident...

When Yamini was in her mother's womb,

it could have been that some rogue cells in her body

started to grow in places they shouldn't...

..but the alternative hypothesis behind teratomas

is almost too bizarre to be believed.

..and then the other theory is what we refer to as the foetus in foetu,

which is the theory of the trapped twin.

A foetus in foetu is when, during the very early stages of pregnancy,

one twin doesn't develop normally

and instead is absorbed into the body of the other.

When they told me that it could have been my twin,

I just called it my evil twin sister,

because it's been putting me through so much trouble!

About 12,000 sets of twins are born in the UK every year

and some research has suggested that up to 12% of pregnancies

may begin as twins,

but then something changes and only one foetus develops.

As for Yamini, although having undergone major brain surgery

to remove what she describes as her evil twin,

she's made a full recovery.

All my symptoms have reversed,

and so I just found this new joy in life.

I suppose having your head invaded by a monster from within

is a pretty unthinkable fate -

but perhaps not nearly as bad as having your brains pecked out

by an unlikely killer on the rampage.

The Bukk Mountains in northern Hungary.

Bats were discovered in a cave with their brains removed.

Local naturalist Peter Estok had heard a grisly story

that pointed to an unlikely culprit.

I was very surprised, and I could not really believe that story.

So, we came to the cave and see it for ourselves.

It's usually birds of prey, like hawks and owls, which go for bats.

But what Peter discovered went against all his expectations.

I couldn't believe what I saw.

Peter found a bird in the gloom...

..but this was no bird of prey.

Suddenly, a tit, a great tit, entered the cave,

and it was looking for something near the crevices.

Great tits? In caves? Surely they couldn't be to blame.

We're more used to seeing them in our gardens.

When they're not feeding on nuts and seeds at the bird table,

the largest prey they are likely to dine out on

are small insects and spiders...

..but these great tits weren't searching for creepy crawlies.

After some several minutes,

we observed that the tit got a bat in its beak

and it started to eat the bat.

And this wasn't just an unfortunate one-off.

We saw several occasions when great tits managed to get bats.

When they were eating the bats, some of them were still alive.

One of our favourite garden birds had gone bad.

But what could turn a sweet little great tit

into a vicious bat-hunting killer?

Great tits aren't the only species

to track down and eat things out of the ordinary.

Over in the States, a couple caught this vegetarian on camera.

It's got a bird.

On the ground, Michael.

Yeah, there's a bird on the ground. It's hurt.

The culprit is a white tailed deer, munching on a chick.

He's got it in his mouth.

He's got the bird in his mouth.

Oh, my goodness! He ate a bird!

Michael, he ate a bird!

He ate a bird!

- Did you see that? - Yeah.

It's not the kind of thing you see every day.

Experts think it was either supplementing its diet

with a quick protein-rich meal,

or trying to get the calcium it needs to grow strong antlers.

So, animals will find new sources of food when needs must.

And with the great tits,

Peter had a hunch what might be making them search for unusual prey.

In hard winters,

it is difficult for the great tits to find food outside,

especially when the snow cover is significant.

So the great tits were starving.

As soon as Peter put out an alternative source of food,

they stopped hunting the bats straightaway.

They only did it in times of extreme hardship.

This is not the first time that we've seen great tits

finding a different source of food when things get tough.

Back in the day, when milk was delivered to our doorsteps,

great tits learned how to peck through the foil

to get to the rich cream at the top.

Something completely out of the ordinary,

in terms of their usual diet.

This behaviour was then passed from one bird to the next,

simply by copying one another.

And then, from one generation to the next,

as the great tits turned out to be excellent social networkers.

In the cave, the birds were seen to be attacking the bats over

a period of ten years, yet great tits only live till they're about two.

So, scientists think that the birds were passing the behaviour

on by watching one another, just like the tits and the milk bottle tops,

only a little bit more gruesome.

Vampire great tits. Sounds like a cheap sci-fi movie, doesn't it?

What could we add to the plot to improve it? Um...

How about...some green balls?

Australia in 2014.

Sun, sea, sand, surf,

and strange sightings on a beach in northern Sydney.

The sands of Dee Why Beach

were transformed into something of a Martian landscape today,

covered in green alien balls.

I'm not sure what they are.

I haven't heard anyone who does know what they are, actually.

They're crazy.

They could be anything. They could be aliens.

But could there really be an extraterrestrial connection?

So, when these strange green furry balls

washed up on the beach in Australia, lots of people were really confused.

Bizarre as they may be,

Mark thinks there's a surprisingly sensible explanation.

These green balls are basically a type of algae.

Algae are very simple plants, but they're really important

and they use sunlight energy, like land plants,

to photosynthesise to produce food.

Algae usually grow on rocks or the sea floor,

but they can grow just as happily drifting in the currents.

But in this situation, they're doing something rather unusual.

Each little tiny colony, bit by bit,

is rolling around on the bottom of the sea

and as sunlight energy hits the top of the ball,

it grows a bit, and then it rotates and then it grows a bit -

and that means the growth is kept even,

and slowly getting bigger and bigger, as the seasons progress,

until you get these wonderful green balls.

But why did these balls suddenly turn up on just one beach in Australia?

That mystery of their occurrence and then their disappearance

is something we still don't really understand.

Maybe in that one bay for a short period of time,

local environmental conditions were just right

for this rotation and growth to occur -

and then maybe something happened.

The currents shift, the water got colder, the nutrients changed,

and the phenomenon stops,

and this is one of the mysteries of these little organisms.

It can occur in an individual water body, like a lake,

for several years and then stop and never be known to occur again.

So, what's seen as a strange anomaly down under...

Well, take a trip to Japan and it's a different story altogether.

Here, Lake Akan on the northern island

has been home to these furry wonders for years.

THEY SING

They're so revered that every year,

the indigenous Ainu people hold a three day festival in their honour.

They're seen as something of a national treasure.

The Japanese also keep them as very low-maintenance pets.

I mean, you'll never need to go out in the rain to take these for a walk.

And if you haven't got room for an aquarium,

you could buy the cuddly toy instead.

TOY LAUGHS

So, the strange green balls on the beach in Australia

were green algae rolled in to balls by the movement of water,

and not unidentified floating objects, after all.

So, a monstrous tumour caused a major headache

for one student in America,

whilst brain-hungry great tits spelled the end

for some bats in a cave in Hungary...

..and some strange green balls triggered

a bit of a commotion on a beach in Australia.

And if you think that's the end of it

when it comes to weirdness in our world,

we're only just getting started.

Next time, we'll discover what causes a beach combing trip

to end in disaster...

As I looked down, there are flames shooting off of my shorts.

..why a flower chooses to smell like a corpse...

It's really doing a good job of pretending to be a dead animal.

..what's causing three suns to miraculously appear in our skies...

..and why a person with perfectly good eyesight can't even recognise

her own children.

It's funny that we have so many pictures of them,

since I can't tell them apart.