red leg crab died

[me03]

Came into work this morning and noticed my red legged crab had climbed out of it's shell and died. Everything else seems to be with in normal limits. Crab was doing well until last week when I added a ricordia mushroom and some polyps. Began to see less action out of the crabs. My second one settled on the rock below the polyp and seems a little listless. My question is what happened and should I be concerned? Advice would be appreciated.

[Satchmo]

It may be that the crab molted. Looks very much like a dead crab. Wait a few days, and when the crab's new exoskeleton has hardened, he'll come out of hiding.