Hermit crabs what's going on?

Ok so 2 of my hermits were very active just yesterday. Running around the tank almost non-stop. And then to they are both hidden under rocks and backing into thier shells to the point that they are not seen. This is live rock only tank. So known predators. Any thoughts?

 

Naps?

 

Possibly molting

 

Yeah they're lazy bastards, those crabs. As soon as you put em in, they eat like crazy, then sit around and gorge for a whole day or two, then eat, then gorge. It's normal to catch mine sleeping quite often....

 

My little striped leg became fond a spot for sleeping in the rocks. The only problem was that once he got in, he couldn't get back out. I had to rearrange that part of the tank so he didn't kill himself in there. Dumb as a bag of rocks, I tell you.

 

a had a tiny hermit crab that found a giant shell. it is the clumsyest thing ever i look at my tank see sand fly up and i see him on his back. he can barly flip himself over too. somehow he has not been eaten yet

 

guess they were nappin....they are and running again. just kinda worried me. everything that is in my tank now is thriving so well, but when i put something new in, they die in about a week.

 

+1 mine do this when they want to molt. They must feel safer in rock crevices.