honestly not sure what happened, they've both been in this cage for about 4 months without a problem, and the cage before that had the same decorations as far as rock and heater and substrate. i'll hit the store and find a container to keep him in while in the cage, because of the size of the cage it's not practical to change the substrate till he's better, and i don't have another place to securely keep him. my best guess is he started to shed and got the skin caught on something and it wasn't ready to come off yet... looks like a bigger version of something that happened to him when i first got him, only that time was caused by me peeling the shed off him....i know better than to do that now.