They are dominantly sessile. The two most important subclasses of anthozoa are the octocorallia and zoantharia. The subclass zoantharia is the largest and most paleontologically significant anthozoan group because it includes most corals and important groups of sea anemones. The most important groups of corals are the Tabulata, Rugosa, and Scleractinia. Horn shape, or honeycomb arrangement in colonial forms.
Bryozoans are often twig or fan shaped.