Coenosteum
In corals, the coenosteum is the stony skeletal material secreted by the coenosarc, the layer of living material lying between the corallites. The coenosteum is composed of aragonite, a crystalline form of calcium carbonate, and is generally a spongy, porous material. Sometimes the coenosteum has ornamentation such as ridges and beads, visible as raised areas of the coenosarc. The coenosteum and corallites together are known as the corallum.
