My crab didn't make it. He was in a too large shell and was alive for a while but never moved. Then today I found him - he had switched to a smaller shell but he was dead in it. He tried to hard to live by trying to switch into a new smaller shell but it was too late. Now I don't know what to do with my other crab -I think he's molting because I found several hollow legs around the tank . Is it ok to leave him in the tank even though another crab died in there?