mother-of-pearl; nacreous layer
Refers to the iridescent inner layer of a mollusk shell, often used in jewelry and decorative arts.
真珠層は貝殻の内側にある美しい層です。
The mother-of-pearl layer is the beautiful layer inside the shell.
Compound of 真珠 (pearl) and 層 (layer). The exact historical derivation is straightforward; the spelling is conventionally associated with the meaning.