ok so one of my fiddler crabs likes to climp to the highest point of the tank and then start waving his big claw into the air. what does this mean? Also one of the crabs just molted it shed its shell and I thought that it was dead but it was just a shell. I have heard that the shell has a lot of nutrients in it if they ate it so should I leave the shell in the tank with them and also how long does the molting process take? how long until the crabs new shell hardens?