OKay, this sounds completely crazy, but my live rock is ALIVE! Seriously, it opens and closes. When it is open, it has soft tissue that opens and you can see inside it and it has like soft teeth in there. The outside of the "rock" looks much like a clam with the ruff texture, but then it continues and atatches to a rock. Can someone please tell me what this think is? I am thinking something like a clam or an oyster maybe? It can be startled like my clam and will close quickly also.