Ooooooo! Is that a sparkling ruby at the end of a delicate, silver necklace?
No. No, it's not. Silly.
It's a bonny thing, nonetheless. It was found in the depths of the Gulf of Mexico and is remarkable in having every characteristic of the ruby, save that it is an animal instead of a gemstone. It has already a sinister history involving many murders, though there are no vitriol-throwings, suicides or robberies on record. It's not that bad!
Video: Inner Space Center
It's a Comb Jelly! Comb Jellies are just one of a whole host of gelatinous, drifty-floaty things that aren't jellyfish. They belong to a phylum of their own called Ctenophora, which means "comb-bearer". They have eight of these so-called combs. Each one is a row of tiny hairs called cilia, which beat to and fro so that the Comb Jelly can slowly make its way through the water.
And the necklace? This is a pair of long, retractable tentacles used to capture food. Just look at how the Comb Jelly spreads them out like an enormous bear hug. They don't sting like a jellyfish, instead they're sticky so that tiny crustaceans get caught and eaten. I don't know about you, but a sticky, murderous necklace doesn't sound ideal for my neck!
That glorious red colour is looking good, though. The only problem being that water is really good at absorbing red light, so by the time you get to these depths there's basically none left. This means red animals look completely black against the inky darkness of the deep sea.
Invisibility is a really bad attribute for a gemstone. It defeats the entire purpose! What a terrible necklace. Cool animal, though!