I have a lot of these really tiny white starfish in my aquarium. I'm 95% sure they are asterina starfish, however, I do sometimes see them on my polyps. I have lost a few smaller polyp colonies because they seem to "melt" away. I just looked at a polyp that was "melting" and noticed that a small starfish was on it. Are asterina starfish harmful? If so, how the heck do I get rid of them?