Ive had asterina stars for as long as ive had this tank and havent bothered me. They arent the coral eating variety so figured they'd be part of the cuc. Recently I wondered why i didn't have as much coralline as I've had in previous tanks and suspected the little buggers. I added a pair of harlequin shrimp to clean them up and bam over night it seems like all the asterinas are running for the hills(or glass). They're literally all over the glass and bunched up towards the water line. I thought this can't be a coincidence and a quick google search shows others experienced the same. So fascinating!