Crab ID Please

[Reefmack]

I brought this one home from my SW lfs on some live rock with shrooms on it. I know most folks don't like crabs of any kind, but can anyone ID it?

http://i153.photobucket.com/albums/s205/mackwork/crab.jpg

Thanks. I have no fuge so he either goes in the tank or doesn't.

[graveyardworm]

Looks like a mithrax ( emerald ) crab.

[Reefmack]

Thanks. I've put him in the tank & hopefully he'll stick to algae & not eat any of my polyps. Looks a lot greener now that he's in the tank.