Although leather corals are soft corals, they are classified as Cnidarians, which categorizes stinging celled animals. They are also part of the Octocorallia (or Octocorals) group, which means they usually have an eight-fold symmetry or eight-branched tentacles.

Just like most corals (mushroom corals as an exception), leather corals are colonial sessile animals, meaning they do not move. This means that your leather coral will stay anchored firmly to a rock or substrate, where it can encrust.