I had one for about a year in my 75. Fairly deep sand bed and it neither starved nor did it appear to wipe out all the beneficial organisms. Didn't move around that much either. It fell victim to a White Spotted Hermit Crab I added a few months ago. Herminator has also eaten one of my snails but I'm still reluctant to remove the guy. Oddly enough, the White Spot is an excellent sand sifter, better than the starfish ever was. He often digs into the sand a couple of inches in no time, stirs it up good. Hasn't bothered anything else in a while and doesn't pick at any of my soft corals, but he's growing fast and I reckon I will have to remove him at some point.