Help Identifying a crab

[iaJim]

Found this on a rock I was taking out of the tank today. Anyone have any ID or information on this guy? Should he stay a resident of my tank? I've had some zooanthids disappearing, and wondered if he was the culprit. About 1/4" x 3/8". Also posted this in the general discussion forum.

Thanks.

 

[LeslieH]

It would be better to have a picture of him in a dish filled with sea water. Right now it's hard to make out its shape.

 

[iaJim]

Here's a shot in a dish. Much better pic. Thanks!

 

[LeslieH]

Thanks for the second shot. It's a pebble crab of some sort, family Xanthidae. I couldn't find the exact species in any of my books. Xanthids are mainly predators so it's not reef safe and a refugium is an excellent place for it.