Maybe you've already seen the video below; it's the latest viral hit (I saw it on io9, myself). According to marine biologists, the answer to your inevitable question of "What the fucking blue hell is that thing?" is, it's a rare kind of jellyfish. But here's what I think, when I look at something like this.
Right from the get-go, I know it has to be an Old One; and since it's in the ocean, that narrows it down (mostly) to Cthulhu and Dagon. Then again, it could be a minion. The point it, this is definitely a Lovecraftian monster, and that means all kind of unspeakable horrors...and, if your mind works like mine, speakable kink.
Now, since I'm such a fan of EMC, my next thought is that it's obviously a Lovecraftian monster designed to MC unsuspecting divers. Obviously, it billows like that to mesmerize its prey.
At this point, my old-school-Stephen-King-fan joins the party, reminding me of an short story called (IIRC) "The Raft." In it, a group of teenagers gets stuck on a wooden raft in the middle of a lake, corralled by some sort of oil-slick-like monster that tries to lure them into its clutches with flickering lights. In one of the few scenes I still remember, a pretty girl is leaning over the edge of the raft, staring right into the predator's metaphorical eyes but too far gone to realize what she's doing.
Sadly, King's monster only kills its victims. But the video below makes me think of all kinds of other possibilities. Maybe this Lovecraftian monster embraces its prey and sucks, not the life, but the will out of them. Then perhaps it coats them in its own squicky effluence, creating a sort of Cthulhian pearl. Something that appeals to its own very specialized sense of aesthetics.
After that, the only question remaining is whether the monster hoards its pearls in some deep-sea treasure hold, or whether it sends them back to the surface to lure more recruits.
But why don't you answer that question for yourself?