COSMOID SCALE
cosmoid scale: translation
scale with four layers, an outer, thin, porous layer of vitrodentine (sometimes denticulate or lacking denticles, adenticulate), a middle layer of dentine with pulp cavities or canals (cosmine), a spongy deeper layer of loose spongy bone containing osteoblasts, and lastly a laminar layer of isopedine with osteocytes and Sharpney\'s fibres. Grows by adding to inner layer only, e.g. Crossopterygii, Placodermi; not found in extant fishes