Spore still has a lot of life left in the game, so I still have high hopes for the Aquatic Stage to be implemented back into the game’s design by an expansion. If you followed Spore since the early days, you would have remembered the GDC 2005 video with Will Wright discussing the game, playing thru the Aquatic Stage. Sadly it had to be cut as the animation did not flow right and was too complex to program. Perhaps they’ve been secretly at work trying to solve their problems…
ConnorJack discusses more about the underwater stage in his editorial which you can read here.