hermit crab alive or dead?

Question
hello
i've had 4 hermit crabs for a few weeks now. they all seem to be doing well. i have de-chlorinated water for them that i've been putting a pinch of salt in once a week. i just got them another water dish so they can have one salt, one fresh. i was going to put it in today when i discovered one of my crabs completely out of his shell. he wasn't moving at all. i thought he might be molting so i left him alone. he's still there and it's been about 10 hours. he isn't buried under the sand at all. it doesn't look like he's moved at all either. he's in the door of the coconut house and another crab tried to go in and moved the shell-less crab a bit and it didn't flinch or react at all. i fear he might be dead. how can i tell if he's dead or not?
i don't have any gauges yet however i put a heating pad under part of the aquarium often and mist them every few days.

Answer
Does he smell like anything?

You really need gauges because there is no way of knowing the true readings without one. Crabs don't often leave their shell to molt, a crab that is out of it's shell is in trouble. Try picking him up and dipping him in some cool dechlorinated water and see if he reacts.