What does the exoskeleton look like?

[hermiehomie345]

I have a PP about the size of a ping pong ball who I think may be surface molting. He has attached himself to the inside of one of the climbing structures in the tank (it's a skull shaped aquarium decoration with holes to climb through). He typically hides in there, so sometimes when I clean I gently move it to locate him before cleaning. While moving it to check, he remained attached to the side (which makes me feel like he is alive). What makes me really worry is that he simply has not moved in over a week. I found a piece of his claw near him but it is just the hard exterior, not the whole claw. My crabs always molt under the surface so I have never seen an exoskeleton, but I'm wondering if he is doing a surface molt and that is just a piece of his exoskeleton? I'm really worried he is sick or has passed, but there is no smell. I am also moving across the country next week so he has a 30 hour drive ahead of him, so a lot of coordination on top of a potential molt. What can I expect from a surface molt? Is that claw piece a sign of the molt or sickness?

For reference: I have about 6-7 inches of substrate that is a mix of sand and coconut fiber. I keep the tank at 70% humidity and it is usually 75 degrees, but I did notice my heater felt pretty weak recently so the temp has dipped to lower 70's (will be replacing asap).