Aquilonastra starfish (known in the hobby as "Asterina") - some species are fine/helpful, others have been known (at least when in large numbers) to go after corals (almost always zoas).
As a general rule, if the top of the starfish is primarily black, or if it has red/orangish spots on it (like the star in the link below), then it may be harmful:
I had NO CLUE, but figured a few dozen stars would feed a shrimp…guess I was wrong.. added: that’s what I get for inadequate research before purchase I can’t afford $20/week to feed a pair of shrimp, looks like I need to find a tide pool somewhere… thank you...
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