Black Coral

Image: JennyHuang

Weird how it's a Black Coral yet it's the only thing that isn't black.

Black Corals, also known as Thorny Corals, are some 230 species in the Antipatharia order.

Image: hjk_888

Most live in deep, dark tropical and subtropical waters, but they can be found from pole to pole and surface to depth.

Image: kanuck

They come in a huge range of shape and colour...

Image: berniedup

Some are extremely bushy, with lots and lots of branches...

Image: dachalan

Others are just a single spiral, just like that American bank guy's signature...

Image: richard ling

Still others don't even bother with a spiral. It's just a wobbly line!

Image: Nick Hobgood

These simple, unbranched Black Corals are often called Wire Corals or Whip Corals, just like simple, unbranched Gorgonians are. Whoops! But there are a couple differences to look out for.

Image: Nick Hobgood

One difference is revealed by a close look at the polyps.

Image: Lophelia II 2009: Deepwater Coral Expedition: Reefs, Rigs, and Wrecks, NOAA/OER

Each one is armed with an array of stinging tentacles for capturing prey which they share with the other polyps in the colony. But Gorgonians are Octocorals - each polyp has 8 tentacles. Black Corals are Hexacorallia - their polyps usually have 6 tentacles, though some have 12, 18 or 24.

Image: JohnWTurnbull

To see the other difference you'll have to get involved in some violence and gore. How could you?!

We've already seen that few of these so-called "Black Corals" are actually black. But what happens if you kill one and tear off its flesh with your teeth like a sick barbarian?

Image: DanPickedMinerals

You're left with its skeleton. A black skeleton! It's made of a tough protein simply called antipatharin and you can make all kinds of cool stuff out of it. It's even the state gem of Hawaii!

Image: Hexacorallians of the World

It's a little thorny though...

Image: Hexacorallians of the World

So if you do use your teeth to tear off its flesh, be kind to your gums.

Or you could just leave it to look lovely...

Image: Tim Sheerman-Chase

Be it sparse...

Image: WoRMS for SMEBD

Or bushy...

Image: Derek Keats

Reaching for the light...

Image: NOAA Photo Library

Or content in the darkest depths.