To an extent. If not fed well they MAY become predatory. The greens are the worst for that. I'm not certain, but from what I can tell they need to be fairly large before they become hazardous (unless your fish are quite small.)
I would venture to guess that yours is currently pretty harmless.
Awesome little stars :)
They're pretty safe and shouldn't harm any coral. If it gets big, (some can get to well over a foot) they can prey on small fish. Yours looks tiny at the moment though so that's not an issue.