Out of curiosity, he scraped the inner coating of one of the larger shells and found layer upon layer of nacre, or mother of pearl, which crumbled away from the knife.
"The Second String"
Nat Gould
If a pearl-secreting oyster be inherently robust, its defence against assault from without may consist of the strengthening of the interior at the point of attack by deposits of nacre.
"Tropic Days"
E. J. Banfield
Such pearls originate, no doubt, in the ordinary way, but, becoming an intolerable nuisance on account of increasing size, are confined in nacre.
"Tropic Days"
E. J. Banfield