Article Source ~ Atlas Obscura
According to Christopher Kemp, author of Floating Gold: A Natural (and Unnatural) History of Ambergris, ambergris is formed when the indigestible remnants of the sperm whale’s favorite meal—squid-meets up with a malfunctioning, leaky sphincter between the last of the whale’s four stomachs and its intestine:
Curved like a parrot’s beak, the squids’ [indigestible] beaks pass from the stomach, chafing and irritating the delicate intestinal lining on the way. As a growing mass, they are pushed farther along the intestines and become a tangled indigestible solid, saturated with feces, which begins to obstruct the rectum. It also acts as a dam. Feces builds up behind it. The whale’s gastrointestinal system responds by increasing water absorption from the lower intestines, and gradually the feces saturating the compacted mass of squid beaks becomes like cement, binding the slurry together permanently. It becomes a concentration- a smooth and striated boulder.
This process is thought to occur in about one percent of the world’s 350,000 sperm whales, who roam in every part of the ocean except the very coldest. It has led to the very common mis-assumption that ambergris is “whale vomit.”
Ambergris is, in fact, most likely passed by the living whale, or the last byproduct of the dead whale, floating up from its eaten carcass. Ambergris cut from whales is black and tar-like, with a strong fecal smell. The longer it is in the ocean, the paler, smoother and more fragrant it becomes, shaped by the smells of the sea. The most valuable ambergris is light grey and lightweight, and may be peppered with the black beaks of squids, like so many little sesame seeds.
Ambergris derives from a sperm whale’s intestines.