Pleae ID hitchhiker Crab

[marco333]

Was away for the past four days and came home to this guy sitting in the sand in my 4g nano. Must have came in on some live rock.
Questions
What type of crab is it, and is it reef safe.
Also, I could not tell if it was dead, or simply a shed exoskeleton. When I picked it up it fell apart, and it was hard to tell if there were any guts inside, so I'm not sure if it is still alive in my tank.
http://img.photobucket.com/albums/v258/Marco333/crab.jpg

 

[meowzer]

I believe black claws means a bad crab!!!! Hopefully you got it, if not...keep your eyes open and if you see it..GET IT OUT!!

 

[burrito]

look like a dead crab

 

[smartorl]

It looks more like a shed to me!

 

[gemmy]

I dunno what it is but that thing is scary looking! (and it looks like a shed to me)