The limestone deposits of certain sea organisms called polyps. Living in colonies, these tiny warm-water creatures take the calcium salts from the sea and build out of them beautifully branched, shrublike structures that are as hard as stone. In time the formations of some types of coral may amount to great coral reefs and the foundations of coral islands. There are different colors of coral, varieties of white, black, and red, the latter being the most costly and most desired in ancient times. (Compare La 4:7.) Tyre at one time was noted for her trade in coral, which was harvested from the Mediterranean, the Red Sea, and the Indian Ocean. (Eze 27:16) Out of the raw coral, craftsmen artistically fashioned various ornaments that were highly prized.

Because of the esteemed value of coral, the Bible makes several interesting comparisons. Knowledge and wisdom certainly outrate the value of coral. (Job 28:18; Pr 3:15; 8:11; 20:15) The same is true of a capable wife; “her value is far more than that of corals.”​—Pr 31:10.