Multicellular life in the oceans would be bound more to the conditions of an ocean than of the non-marine Earth. And while there's some diversity in oceans, muc

Multicellular life in the oceans would be bound more to the conditions of an ocean than of the non-marine Earth. And while there's some diversity in oceans, much of this diversity would be captured in any given ocean. Multicellular life tried a whole bunch of shapes and niches early on. It would be interesting if some of the also-rans in Earth's oceans became the winners in other oceans.