Hey psusocr1,
Check out the thread "Crabs & Shrooms", go to the bottom and check out the crab posted by tnt. Is that the one you got? We just got one. It's HUGE. Our tiggers play with it. Pick it up and shake it, but he hasn't nipped at them yet. I don't know about the other critters, such as the shark, ray or starfish, however, I am sure someone will let you know.
It is a cool crab though, ballsy, but not aggressive toward anything else so far. It climbs over some of the other little crabs we have in there.
Let me know if it's like the one you got, and does anyone know what kind it is?.............Peace