PEARL
Item of great price (Mt. 13:45, 46; Rev. 21:21; Jb. 28:18), used for adornment (1 Tim. 2:9; Rev. 17:4).
Pearls are found inside certain species of mollusks, such as oysters.
They are globules formed from layers of calcium carbonate alternating with layers of organic substance; They are formed by the deposit of the pearly substance around a foreign body that has been introduced inside; a grain of sand, for example, produces irritation and serves as a nucleus.
This substance is the same as the nacre that covers the inside of the shells.
Large, well-formed pearls are produced by the “pearl oyster” (“Meleagrina margaritifera”) which is abundant in the Indian Ocean, especially in the Persian Gulf and near Ceylon (present-day Sri Lanka).