Asterina, agreed. I have a few of them, they are pretty cool (when I see them). Some are reef safe, some aren't, though I have the feeling that many more are safe than not... it's unlikely a coral munching starfish is going to make it all the way into your tank without being noticed (though not unheard of). I'm pretty sure mine are detrivores, since I doubt they could compete as algae eaters in my tank and they don't touch the macros or coralline (good thing, I'd be mad if the pink and burgundy coralline disappeared).
The first one I noticed... that was months ago, there are at least 3 of them in there now.
