Sclerocyte

 ( Sponge Anatomy ) 

Sclerocytes are specialised cells that secrete the mineralized structures in the body wall of some invertebrates.

In they secrete calcareous or Silicon dioxide spicules which are found in the mesohyl layer of sponges. The sclerocytes produce Sponge spicule via formation of a cellular triad. The triad of cells then undergo mitosis, creating six sclerocytes. In pairs, the sclerocytes secrete the minerals which create the spicules.

In starfish they are present in the dermis and secrete the calcite Microcrystalline from which the ossicles are formed. They also function in growth and repair of the ossicles.