Coenosarc and Coenosteum
The coenosarc is the layer of living tissue overlying the coenosteum. Depending on the thickness of the coenosarc, the structures on the coenosteum may be clearly seen or indistinct when viewing a coral underwater. Where the tissue layer is very thick, the skeleton form will be obscured.
The skeletal area between corallites is termed the coenosteum. An amazing array of structures grow on this surface providing key differences between genera.