Translations:AY Honors/Shells - Advanced/Answer Key/144/en
From Pathfinder Wiki
The outer edge of a mollusc's mantle contains glands that secrete color pigments during shell formation. These pigments control the colors on the outside of the shell. The iridescence on the inside of the shell is caused by alternating layers of calcite and aragonite refracting different wavelengths of light by different amounts depending on the viewing angle.
