There's a lot of cool ocean animals! My favorites are probably marine flatworms though, there's so many beautiful varieties. Also if you want to know just a lot of really insane facts about the oceans and the creatures that live in it I highly recommend Sex in the Sea by Marah J. Hardt. It really opened my eyes about just how WILD life on earth is, and has encouraged me to get a lot weirder with my fantasy world building. :^)