I don`t know what the name of it is,but I`ve been told and have read that "hairy" crabs like that shouldn`t be left in the tank if you have corals.If he was in my tank I`d chuck him in the sump.Good place for things of interest that you don`t want to leave in your tank.
Pat
According to Fenner/Calfo's "Reef Invertebrates", the "hairy vs. nonhairy" is pretty much a myth. You're supposed to look at the claws to see what they eat (or direct observation). Fenner/Calfo show photos of smooth crabs that are quite destructive.
I have some of these crabs myself, and I've observed them assaulting snails.
Hy, there are crustacean bulletin boards that are used by academics. Find one of these and latch onto an expert. These pocket-pen-protector nerd types would love to break the monotony of their babble by having a specimen photo to identify
I cycled a 10 gallon tank once with a smooth white crab.. that tore up ANYTHING living or dead. If it was ingestible he would eat it.
Which was fine... he was the only living thing in there. Such as it goes with most things from the north atlantic waters of Maine.
I found that with careful acclimation, plain crabs and the hermits down in the tide pools will convert to warm tropical tank water. Non are reef safe (I didn't even need to try) but to study them and watch them hunt and feed is endlessly fascinating.