Another unknown crab - ID help?

[SurlyT]

Sorry to post yet another one of these messages, but I have yet to find a good pictorial index of marine aquarium crabs anywhere online (suggestions appreciated if anyone knows of one).

Saw this little guy for the first time tonight - in a 12 gal. nano tank I've had for two+ years and I haven't added any new liverock since the initial setup. So he's been in there quite a while.

He's very small (compare him to the button polyps he's moving through) and very fast, so these two pictures were the best I could do before he vanished again.

I'm not really worried about him since he obviously hasn't caused any problems that I'm aware of, but I'm still curious. Any ideas, folks?

 

[charlesr1958]

Going by its spoon shaped claw tips, I would say its a mithrax crab, usualy harmless while small, content to scrape the rock for algae and small inverts, hence the shape of its claw tips. I have however seen large specimens become quite destructive and become a hazard to polyps such as zoanthids.

Crab Hitch Hikers

Chuck