I got a bag of shells, thinking my Hermit would like to change soon (looked big for his current shell), I rinsed and put the shells into the tank, and he immediately went to investigate the shells. At first he went into a small conch(?) shell, but decided it was too big, then he found another shell, and went into that. He looks much happier now, but what should I do with all the other shells? Should I take them out, or just leave them in there? It's sort of making the tank bed look crowded.