Crab ID and what to do with him

[ScubaSteve]

Hey all,

I caught the crab that I suspected that might be snacking on my Xenia and rearranging my frags. Before I subjected him to the great porcelin fish bowl I wanted an ID. I try my hardest to not get rid of things but I don't want him to become a monster. If he's harmless I can put him back.

I think he might be a xanthid. Four sets of walking legs, the last pair he usually keeps up in the air. Fan shaped carapace and pointed claws. Opinions?