Sometimes, in a wider sense, applied to all the Anthozoa, expert the Alcyonaria, whether forming corals or not.

The only exceptions to this structure are found in the arrested or modified zooids, which occur in many of the colonial Alcyonaria.

In the zoophyte branch, class Alcyonaria, one finds the order Gorgonaria, which contains three groups: sea fans, isidian polyps, and coral polyps.