Sorry for photo quality, the tank's on the ground at a weird angle. I can try for more pics if needed.
This is Pilumnus sayi, the Spineback Hairy Crab. I found him at about half an inch across in March, on some live rock, and he's now a good 2-3" across. He'll hit about an inch across in the carapace, so he's nearly full size. Fairly hardy as saltwater animals go.
I chucked him in a tank with some spare live rock back in march, and he's been growing well with very intermittent feeding, so he seems to be eating algae and whatnot. Definitely not to be trusted with anything he can get his claws on, though so far he's ignored the rock flower anemones. He'd be a really cool sump or refugium animal, particularly if trained to take food from tongs to show off to guests.
The tank he's in has been fallow for 72 days on October 1st, so ich hitchhiking shouldn't be a concern. I really do want to find him a good home, as I'm planning to break down the tank he's in. He's not to be fed to a puffer, used in animal fights, or otherwise wantonly killed; I'm attached.
Willing to consider driving or shipping. I'm near Austin.