In corals, the coenosteum is the stony skeletal material secreted by the coenosarc, the layer of living material lying between the corallites (the stony cups in which the polyps sit). 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.
- Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. pp. 134–135. ISBN 978-81-315-0104-7.
- "Coensarc and coenosteum". Coral Hub. Retrieved 2015-04-23.
- "The polyp skeleton". Corals of the World. Australian Institute of Marine Science. 2013. Retrieved 2015-04-23.