While it is a scale worm it's definitely not Lepidonotus clava. First off, members of the genus Lepidonotus have 12 pairs of scales while this guy has 18. Second, L. clava is from cold subarctic waters & isn't going to be found in a tropical reef tank among Halimeda or Caulerpa! It's a predator on small organisms like other worms and crustaceans. You don't have to worry about your corals.