| It has not really been discussed on the pearl forum, but the operculum has a fascinating makeup....
"The operculum is not a product of the mantle. It is produced by a separate organ, the opercular disc, a pad of specialized secretory epithelial cells located right where the operculum is attached - on the posterior, dorsal aspect of the foot. The opercs of some species are secreted spirally, with new material being deposited on one edge only, and the operc gradually rotating on the opercular disc as it grows. Others are secreted concentrically, with new conchiolin being deposited on all edges of the operculum simultaneously, without rotation of the operc."
Slraep |