Is this a black emerald?

[ReefinVic]

Is this a black emerald crab or gorilla crab?

If it is black emerald, is it reef safe?

 

[S-t-r-e-t-c-h]

Definitely a mithrax sp. crab (a kind of emerald crab); generally safe, but any crab can potentially be an issue.

 

[Palyzoa]

Looks like an emerald crab. Good algae eater but some people report them eating corals.

 

[ecdragonz]

Just have to watch them.I had them eating my zoa.

 

[Michael Cronmiller]

Had one eat up a chalice, and eat up some zoa's before I could catch him