Ha ha, reminds me of the White Spot Hermit (Dardanus megistos) I had for allmost a year. Should have known better and researched before buying. He was still fairly small at the LFS, missing his big claw and looked so colourful and cool, I couldn't resist.
He was about the best sand sifting critter I've had in my system but he grew pretty fast, moulting every two weeks or so. Grew back the big claw and things started getting interesting after a couple of months. Had to find some extra large shells for him at the Dollar Store 'cause he outgrew them pretty quick.
As I said, great sand sifter and very entertaining to watch but as he grew some of my other inverts became meals between his sand sifting duties. He chewed up my sand sifting starfish, one large snail and two pencil urchins. My brittle stars didn't even come out at night anymore and one lost part of an appendage, I suspect to the 'herminator'. He also did a fine job of fragging my hammer coral into three parts. Didn't eat them, just so big and clumsy, he walked all over everything. Still, he was a riot, I saw him launch himself from the live rock from almost 2/3 rds of the way up and land on the substrate, a jumper!
But alas, being the opportunist that hermits are, with his size he was getting too destructive & had to go, no sump to put him in. I brought him back to the same LFS, at least 4 shell sizes larger and with both of his claws. Didn't get any credit and didn't really expect any, I enjoyed having him and still think I got my money's worth, if only in experience...
Here's a pic from a while back. Yep had an algae issue. The small blue legged hermie hitching a ride on his back was hilarious and provides some sense of scale as to his size. I saw him try to munch the small hermies a number of times, but they were smart enough to retract way back into their shell and herminator's huge claw just couldn't get in there so no small hermies were lost to the dude. The pencil urchin in the background was not as fortunate, he's already missing some spines in this photo.
