Pest crab?

[crashrat]

Last week when I was basting my rock I blew a crab shell that was shed the size of a quarter. It looked like an emerald crab but I could not positive ID. I do have a Sally light foot but no emerald crabs so this was a hitchhiker. Today I saw a claw reach out from the middle of a rock, so I know he is alive and feeding, but have yet to see him. My question are there any known pest crabs that can do harm this size and looks like an emerald ? Are emeralds this shy? Recently I have noticed some zoo's thinning out and can't find the source.
Thanks

[flyyyguy]

odds are he is a xanthid and not your friend

you can look here to see if it looks familiar

http://www.chucksaddiction.com/hitchcrabs.html


get a glass heavy enough to not blow in the current, lean it up against your rocks at an angle and put some bait inside. They are often fairly easy to catch

[crashrat]

I was affraid he wasn't a good guy, thanks for the help flyyyguy.