The world of prehistoric life is a fascinating one, teeming with all sorts of bizarre, unique, and otherwordly creatures that vanished millions of years ago. This, coupled with the fact that many were gigantic, means they are a vivid source of imagination for many and various interpretations can be made out from them. While the dinosaurs are undoubtedly the most famous (and most favored) prehistoric creatures, that's not to say that life in the seas was any less mysterious than its terrestrial.