Those of the anthozoa are further divided into 2 new classifications. The first is the scleractinian (the extant
stony corral), and the tetracorals (the four sided corals). Those in the scleratctinian have a hexagonal pattern on their
insides, while those in the tetracorals have a bilateral inside, contrary to their name.
Like most polyps, they are composed of a tube like body and a row of tentacles around the opening of the mouth. The inner
filling between the 2 layers is relatively thick and make up a large percentage of the organism's body mass.
Some organisms in this class are the sea anemones and other organisms that are anemone-like, both those with skeletons
(such as the scleratctinian corals) and those without (tube anemones). There are classes of these organisms, aside from the
first classification discussed earlier. The first is the Zoantharia, which includes the "true" corals and most of the anemones.
The second is the octocoralia which includes sea pens, sea fans and "soft" corals. The last group, called the Ceriantipatharia,
are very rare and aren't found easily in the fossil record. They are the burrowing sea anemones and the black corals. All
of these compose the class that occupy a large percentage of the sea. This last group is controversial because some scientists
believe they do not form a third group but instead should be grouped within the earlier two groups.
