Hagfish. there's a reason I never draw anthro hagfish, despite using one for my name and icon. no limbs, no eyes beyond flat black spots, no bones, no jaw, not even a sucker mouth like a lamprey, it sort of turns the first bit of it's mouth inside out to rasp teeth against its food (often dead whales). it's basically a slightly flattened worm that makes slime. though I did once draw some in clothes http://fc03.deviantart.net/fs31/f/2008/233/f/9/mmm__slime_eels__by_phoenix_feather.jpg just can't make them look at all humanized while still keeping them recognizable as hagfish.