nacre

In this case, the formation of nacre layers of different thicknesses may appear random, but is actually dependent on the thickness of previous layers.

A pearl’s symmetrical growth as it lays down layers of nacre relies on the mollusk balancing two basic capabilities, Otter and her colleagues discovered.

The floor was made of mats woven from strips of shell-nacre, bound at the sides with an inch border of pink coral.

The specimens collected by Mr. Schoolcraft, vary much in the color of the nacre.

He lifted a small hammer and struck a velvet-voiced bell that stood on the Arabian table of cedar inlaid with nacre and ivory.

Purplish bivalves and enormous nacre-lined conch shells lay upon the tables.

In the lower part is a dark clay with Pholadomya margaritacea, still preserving the pearly nacre.