Thank you everyone! I was a little afraid of using the live fish - but since it was my idea I figured I'd better pull it off!
sofiasmami: Thank you. The rolie polie olie was supposed to be a cake in his shape, not just with him on top. That's why it was a disaster... but it worked out in the end, and the mom was happy
cakefanatic: The shells are all white chocolate. I shook them in a plastic baggie with "silk white" luster dust, because the bride didn't want a really pearlized look. The little pearls, though, were shaken with super pearl dust.
Thanks again to everyone for your nice comments!