I wouldn't worry about them. They will start to subside in a few weeks/months and are great filter feeders. Sort of unsightly, but more will just pop up if you scrape them out. It's one of the later stages of a new tank settling in. I think I first saw them like.. at 2 months of age of my 55g and they went away except for a few in another month or two. No harm to corals. Consider them a good sign your tank is aging well