These appear to be Star Polyps - Briareum - and depending on the lighting look either pink or faintly green. In strong current its base will spread across nearby rockwork, and extended thousands of individual polyps when the tank lights are on. At night they are fully receded into its mat. Some consider these to be a weed-like nuisance, so isolation may be in order. Great beginner coral for new coral keepers, but after a while you may want to replace it with something nicer.