he just crawls around on the sand bed... about 3-3.5 inches in diameter. I've seen him on the glass once, other than that he stays on the bottom. He's never (that I've seen) crawled on top of my rocks or any of my corals. When he goes underground, he looks like he's just sinking into the sand, it's pretty cool.
I think my sand bed just needs time to recuperate, and a larger tank would likely be a better home. The next one I set up will be a 120, but I've got a while until then so I need to make arrangements to keep him fed. From what I understand he feeds on the detritus and microfauna in the sand bed, though I've read (and not observed) that they can be spot fed meaty foods.
Astropecten polycanthus is the scientific name, I think. The majority of the photos on google image search match what I have.
