reef4ever, those are asterinas. Typically they are harmless, however if you see some that are bluish in color (in your tank), they may eat SPS corals. I had this problem in my reef tank and would extract as many as I could. The odd thing was in a bowl on the kitchen counter, they would appear to be green or brown in color. In the tank, they would look blue or white. The white ones are safe. The blue ones are the problems.
Eventually I just got a couple of Harlequin Shrimp to eat these guys, wiping out any potential problems.
So to answer your question, odds are yours are fine. The blue ones aren't common at all. Few people report about them, in my experience.