The scleractinians are solitary or colonial corals in which the septa
grow in multiples of six, and they are the most important and abundant
of the modern corals. These corals were the dominant reef builders of
Mesozoic and Cenozoic seas, and their remains are common in many of the
marine formations of the State. Plate 16 illustrates some typical
scleractinian corals from the rocks of Texas. This order has also been
referred to as subclass Hexacoralla, and its members have been called
hexacorals.