Yeah I agree you really should put that crab in a species tank if you like it that much.I had a box crab that came in as a hitchhiker with liverock that I bought.It ran havoc on my tank and me,eating snails,other crabs,peppermint shrimp.It won't be amusing later especially if you have coral in there.Besides have you ever smelled a dead snail shell,it reeks!!!