OSS-i-kulls Calcium-containing structures in echinoderms' coverings. 523
primary building blocks of the internal skeleton of starfish; made of magnesium calcite and arranged to form lattice-like structures joined by connective tissue; strength of the skeleton depends on the amount of space between the blocks of skeleton
The numerous small plates that constitute the echinoderm skelton. These ossicles are composed of a form of calcium carbonate known as calcite.