There are two main classifications for corals: hard coral (scleractinian and stony coral) which form reefs by a calcium carbonate base, with polyps that bear six stiff tentacles, and soft coral (Alcyonacea and ahermatypic coral) which are pliable and formed by a colony of polyps with eight feather-like tentacles. These two classifications arose from differentiation in gene expressions in their branch tips and bases that arose through developmental signaling pathways such as Hox, Hedgehog, Wnt, BMP etc.
there are two main classifications for corals hard coral (scleractinian and stony coral) which form reefs by a calcium carbonate base with polyps that bear six stiff tentacles and soft coral (alcyonacea and ahermatypic coral) which are pliable and formed by a colony of polyps with eight feather-like tentacles these two classifications arose from differentiation in gene expressions in their branch tips and bases that arose through developmental signaling pathways such as hox hedgehog wnt bmp etc