ambergris

ambergris (ămˈbərgrēs) [key], waxlike substance originating as a morbid concretion in the intestine of the sperm whale. Lighter than water, it is found floating on tropical seas or cast up on the shore in yellow, gray, black, or variegated masses, usually a few ounces in weight, though pieces weighing several hundred pounds have been found. Ambergris has been greatly valued from earliest times. It is now used as a fixative in perfumes. Its active principle is ambrein, a crystalline alcohol with the empirical formula C₃₀H51OH.

See C. Kemp, Floating Gold (2012).