Character design for class. Lord Osedax is a 1,000 year old tube worm that feeds on the souls of drowned sailors. When an A'Apuan raiding party accidentally stumbled into his grotto, he devoured them, and now rides on top of one of their numbers animated corpses.
The name Osedax is actually a species of tube worms, by the way- I found this out- that live in the dead remains of whales. The name is latin for "Bone Eater". Fantastic.