I noticed my yellow mystery snail in one place, with his trap closed. I thought that was strange, so I put him in a bowl with a bit of food. After a long while (over a half hour) he slowly did come out and seemed to eat a bit. So, at least I knew he wasn't dead. I put him back in the tank last night, and this morning, he is still in the exact spot, closed up. Something is definately wrong but I don't know what. Any ideas what to do? Should I just leave him and expect him to die?