Hexacorallia is a subclass of Anthozoa comprising ~4,300 species of water-based organisms formed of colonial polyps generally with 6-fold symmetry. This includes all of the stony corals, which are vital for coral reef formation, as well as all sea anemones, tube anemones, and zoanthids within six extant orders. They are distinguished from the other subclass of Anthozoa, Octocorallia, in having six or fewer lines of symmetry in their body structure and only single rows of tentacles. These organi… (More on Hexacorallia)