Periostracum
As periostracum is called an outer organic layer on the shell at mollusks (molluscs) and Brachiopoda (brachiopods). This consists of conchiolin , a protein mixture tanned and sclerotized by quinones. The periostracum is followed by 2-4 layers of calcium. The periostracum serves as a protective layer for the underlying layers of the shell, for example against the effects of acids or boring predators.
See also: cuticle
swell
- Lexicon of Biology. Volume 6, Verlag Herder, Freiburg im Breisgau, 1985, ISBN 3-451-19646-8 , p. 330.
- Lebensmittellexikon.de