Definition of prismatic layer in English:

prismatic layer


  • The middle layer of the shell of a mollusc, consisting of crystalline calcite or aragonite.

    • ‘As a result, it has been difficult to identify detailed or minute shell structures embedded in the thick prismatic layer or secondary thickening at the shell posterior.’
    • ‘The prismatic layer is the middle layer and is composed of thin blocks of a prism-like calcium carbonate, which are oriented perpendicular to the mantle and the other two layers.’
    • ‘Thinner extensions from the prismatic layer in Pseudobigalea crista also form comarginal ridges.’
    • ‘Besides, the aragonitic shell is made up of two oriented layers: an irregular spherulitic prismatic layer and a fine complex crossed lamellar layer.’
    • ‘This thin, prismatic layer was deposited too far from the shell margins to be interpreted as likely pallial myostracum.’