Crab ID

[Eb0la11]

Hey guys,
so I've had several crabs kicking around in my reef tank for a while. Im certain of at least 2 hitchhikers and also a couple emerald crabs I've put in on my own. I think they are awesome and up until today they have posed no problems.

I want to know if that will remain the case or if this guy is likely a culprit of future problems? The reason Im asking is cause tonight I flipped on my light switch at 11:35 pm and this little guy was climbing on my clam. What do you think of him? He's done no damage to my corals. I've seen maybe 1-2 blue legged hermits get killed, but I dunno if it was him, and if it was, frankly, I dont really care. This guy's too cool to worry about a couple blue legged hermits. Anyways hes about the size of a toonie. Hopefully this picture is enough.