Pyura chilensis

The roads of Hell are paved in cobblestones which wail unceasing into the sulphuric night as demonic hooves and bestial paws crush them beneath their weight.

Should you visit the long, winding passages of that dread kingdom, be merciful, traveller. Never tarry, and let your steps be soft and swift for your boots pound the poor, suffering souls of the damned.

From the outside Pyura chilensis looks like little more than a disturbingly organic rock. The kind of thing a disobedient astronaut might have smuggled out of Mars to decorate his garden, only to regret it when he becomes its first victim. You'd think the peculiar texture and what appears to be a smattering of red sphincters would have given him pause for thought, but you know how some people are about their gardens.

Closer examination by the International League for the Prevention of World Domination by Extra Terrestrial Rocks will reveal that beneath this tough, rocky surface is a soft, visceral centre. It turns out that while we like to eat smooth, creamy centres encased in rich, milk chocolate, the Demons from Mars prefer rocks with guts in the middle.

It's probably about now that an idea truly blossoms: this is probably not a rock. Intellectual insights like this is what will ensure the continuing survival of the human race/destruction of all humanity by our own hand.

What we're looking at here is a tunicate found on the coast of Chile and Peru. More specifically, it's an unusual Sea Squirt who belongs to the same genus as that other lump of lunacy known as the Sea Tulip.

Video: Wolfgang Raab

Like any other Sea Squirt they have two openings to the outside world, one for taking water in, the other for letting water out. Tiny edibles are filtered out as it passes through. You can see these two openings, the siphons, on the surface as those red sphincters. And that tells you that while individual P. chilensis can grow alone, they can also fuse together into great, big rocks covered in red blotches.

Growing together like this is good stuff for mating, since they can only dump their eggs and sperm into the sea. Lonesome ones can fertilise their own eggs if they need to, since they start off male and become hermaphrodite with age. Man bag at the ready...

Image: Stéphane Batigne

Oh, and while I said it looks like a demon delicacy... it's actually a human one. People eat these things! Both raw and cooked. It isn't even a weird eccentricity among a Chilean tribe depicted thousands of years ago in stone relief by ancient civilizations who called them the "madmen who eat stones"... this stuff is exported around the world!

It is US!

WE are the Demons from Mars!