(upbeat music)

(Matt) You're looking at a creature

few humans have ever seen.

This is the crusty nautilus,

which has never before been filmed

and hasn't even been spotted since 1984.

And we see here

that it immediately shows its greatest weaknesses:

cages and fingers,

yet it has a way of escaping things

like fingers and hungry mouths.

Covering its shell is sort of a skin

that feels like wet moss.

Scientists believe this covering helps it slip away

from the grasp of its predators.

Now, I'm willing to venture

that you already know about the nautilus.

They have beautiful shells that are striped like tigers

and have short little tentacles.

Indeed, they're cephalopods

so they're related to other tentacled sea creatures

like the octopus and the squid

but instead of actively hunting like other cephalopods

the nautiluses are largely scavengers.

They spend a bulk of their time on the sea floor

searching for dead fish to eat

and good on them for that.

They can do whatever they want with their lives.

As for the crusty nautilus

it's definitely still a scavenger

but unlike other non-slimey species

of nautilus it shares a habitat with,

it doesn't scrape the bottom

of the barrel that is the sea floor.

Instead, the crusty nautilus will

make its way up the water column

following the reefs into shallower waters.

Here they'll find even more kinds of dead fish

on account of the incredible biodiversity of the reef

But, this migration is not without its problems.

More biodiversity means more predators

and more predators means more bull(beep).

And this may well have been what drove the evolution

of the slimey shell.

With more predators to worry about

and without the safety of the darkness of the deep

the crusty would do well

to have an extra slippery countermeasure.

So it's become the closest thing the sea has

to Slimer from Ghost Busters

only without all the screaming and bad attitude.

So it's got that going for it, which is nice.

(upbeat music)