Grainy hand hermit, Pagurus granosimanus.
A couple of days ago, I caught a small hermit half-way out of his shell, stretching out to snatch another hermit's meal. In one of the photos I took, I got a clear shot of two of the back legs.
They are quite a bit shorter than the front legs, barely the length of one segment. When the hermit is wandering naked, looking for a new shell, he holds his abdomen tightly coiled, with the 4 tiny legs barely visible. Here, they're stretched out to keep a grip on the shell; he'll retreat 'way back into it, out of reach, once he gets that food.