Pretty sure that's a porcelain crab, harmless filter feeder.

Here's a link I picked up, lots of pics, but yours isn't on the list.
http://www.flmnh.ufl.edu/reefs/guami...dae/index.html

here is a pic of a porcelain , scroll down. I don't think that is what you have
http://www.xtalworld.com/Aquarium/hitchfaq.htm

Thanks everybody for the replies
I'll go with the majority and into the DT it goes, right after I sex it

I think noirsphynx may be right and it's a Porcelain of some kind
That means I now have 3 different ones

Yup, pretty positive on it being a porcelain, I've seen quite a few variances working at the LFS and have purchased a few myself. I'm pretty sure porcelains are just about impossible to identify gender wise because if I remember correctly they are more closely related to shrimps than crabs.

OK thanks, good to know
I found another in the rock so I've baited a glass
If the first one is about 1/2", the second is smaller than 1/8" :surprise:

http://i749.photobucket.com/albums/x...psb38e3ceb.jpg

nice freebies , cool looking crabs for sure .

Too cool!

Looks like a porcelain crab to me

Want One lol
 

Ok Greg, you better bring me one tomorrow, lololol,,, the wife likes:)

They are keepers...