Crab molt??

[MarineFlake]

I have my 29G setup, been about 2 weeks now. I have just a couple of pieces of rock and a piece of lr from my 75G. Water params looked stable, so I drop in a crab..nothing special, just one of my cleaners. He's the only one. He's been in there 3 or 4 days now and today I see this, what looks like dead crab. I thought, well poop..However, upon closer observation, the crab is in his shell hanging off some rock, healthy as can be..Where did this mystery crab with no shell come from? I don't think I have ever seen a crab molt, but Ican't get close wnough to see if its just a skele or now..Sure looks like the crab. Anyone?

 

[stusclan]

When my crab molts, it leaves a shell that is identical to itself on rock. I first thought that I had a hitchhiker since I knew it wasn't my original crab. Kindof creepy looking. My peppermint shrimp do the same thing.