Crab Identification ?

Need help identifying a hitch-hicker. Take a look and If anyone has any ideas lets me know. I've got him in quarrantine now but he was in my tank for a least three weeks before he came out in the daylight. He doesn't seem to browse much just waits for me to drop food near him. He's about the size of a silver dollar.
Trey

 

hard to tell does it have long legs that stay close to the ground? if so it looks like a sally lightfoot, maybe a emerald? or um...well lol

 

It looks exactly like an emerald but is totally different LOL. It is Dark brown to almost black in color. If it was green I would say its a large emerald, but it's not.
It's a question wrap in an enigma encirled by a riddle? It's a cool looking crab though.
Trey

 

Mithrax crabs come in more flavors than just Emerald (Mithrax sculptus). Perhaps this is a relative.

 

yum...like maybe ita blackberry crab? lol...like black berry icecream

 

I'm gonna Google that one.... hhmmmm... Blackberry Crab IceCream..... Sounds good

 

Is this the one ??????

http://www.yankeemagazine.com/recipes/search/onerecipe.php?number=4881

 

or u can make this, instead of 2 items its one! http://recipes.epicurean.com/recipedetail.jsp?recipe_no=16506

 

w00t look at this

http://bertc.com/japanese_ice_creams.htm

 

I can't tell by the pic but if the claws are black it is a Xanthid Crab (coral crab). They can cause some problems with eating corals...it also might be a rock crab. I have had both come in as hitchhikers and I keep them in the refugium along with a very large Blue Neon Hermit that is the proverbial bull in the china closet...knocking things over. The other two crabs pretty much just scavenge but I have noticed since taking them out of the display tank that I am not getting chunks takenn out of my mushrooms!!

Drew