Ambergris

Ambergris is a gray or black, waxy substance produced in the guts of sperm whales. Some have suggested it is hardened whale vomit, but more recent studies have shown it is generally expelled from the large intestine along with fecal matter. Lumps of ambergris often contain the beaks of giant squid, a favorite food of sperm whales. Ambergris’ role in the digestive system of sperm whales is to protect the digestive tract from irritation caused by the beaks. 

One piece of ambergris can weigh anywhere from a few grams to 50 or 60 kg. The largest recorded ambergris chunk, found in 1908, supposedly weighed about 450 kg (1003 lbs). 

As Solomon learns in Spirit of the Turtle, ambergris was and still is highly valued in the perfume industry for its striking and long-lasting odor. Dealers in ambergris prize most highly "cured" ambergris that has floated in the ocean for years, seasoned by saltwater, wind, and sun. Obviously the piece found by Solomon and his friends would be fresh ambergris, but it would still have high value. In Herman Melville's Moby Dick, a member of the Pequod crew also finds a fresh piece. He estimates the value at one gold guinea per ounce.

For more information, see:

Kemp, Christopher. Floating Gold: A Natural (and Unnatural) History of Ambergris (Chicago: University of Chicago Press, 2012)