some asterinas are said to go after sps also. i have a few and i pull them out every chance i get. they dont seem to harm anything in my tank, i just dont like things getting out of control. they seem to reproduce very rapidly. i wonder if a harlequin shrimp will eat them at the same rate that they will multiply. that would be cool, then you could have a self-sustaing system for feeding the shrimp. i would just worry that the shrimp will kill all of the stars and then you would have to purchase other stars to feed it.