Coenothecalia

Coenothecalia (also known as Helioporacea) is an order of the subclass Octocorallia that forms massive lobed crystalline calcareous skeletons in colonial corals. These corals first appeared in the Cretaceous period.

The blue coral (Heliopora coerulea), the only species in the family Helioporidae, is most common in shallow water of the tropical Pacific and Indo-Pacific reefs. It has no spicules, and is the only octocoral known to produce a massive skeleton formed of fibrocrystalline aragonite fused into lamellae, similar to that of the Scleractinia (stony corals). They form large colonies that can exceed a meter in diameter. They are composed of vertical branches, or folia.