Is this a commensal crab ?

[gregzz4]

Originally Posted by noirsphynx

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"