Human remains. Like Charley, I read somewhere that the skeleton of an Elizabethan sailor was found, and that he had had syphilis, judging from his joints. Maybe on the Vasa, or the Mary Rose. The skeleton of a dog was definitely on the Mary Rose.

Different on the Titanic. There is a kind of lamprey eel down there that eats whales, let alone humans. The most poignant photo from that wreck was a pair of mens shoes a short way from the wreck, side be side. Looked like some poor sod was wearing them when they arrived there.