Crab ID?

[Venom]

I'm new to reef keeping, I've had a 20g set up for about 5 months and a 75 for about 3 months.
Tonight I found a new critter in the the 20. I added a piece of fiji LR about 3 weeks ago, he must have come in with it or I KNOW I would have seen it before.
Apologies for the bad pic, he was on the wall side of the rock, I just caught a glimpse of him while looking for a marauding stone crab who's been picking off my hermits. I couldn't actually see this guy, I just stuck my digicam around back of the tank and took a few shots of the back of the rock.

Any idea what this is and is it "reef compatible" or do I need to get him out before he picks off hermits and snails too?
I don't think I've seen one like him before.

Thanks!!

-V

crap, I had attached a file and its gone, I'll make a reply and attach again

[Venom]

trying again

[Python73]

That's a porcelain crab. Filter feeder, ofter found around / on anemones. Not a snail eater.

S !

[Venom]

wow, thanks for the fast reply!
that's the closest name I could attach to it as well.

Much appreciated!