What is it? More than two dozen unusual lumps discovered in Italy (such as this one; note hammer for scale) are the first known fossils of ambergris, a waxy substance produced in the intestines of sperm whales, a new study suggests.

Roberto Bizzarri

Stinky Whale Clumps, Now in Fossil Form

Rocky lumps found eroding from ancient clay-rich sediments in Italy may be the first known fossils of ambergris, a fragrant and flammable substance produced in the intestines of sperm whales. What’s more, according to a new study, the large number of lumps discovered within a very small area hints that these fossils may be all that’s left of a mysterious mass die-off of the giant creatures.

Ambergris—Latin for “gray amber”—is a dull, waxy material produced in the intestines of sperm whales. Because squid beaks are commonly found embedded in the lumps, scientists have suggested that the whales produce the smelly substance to protect their lower digestive system from indigestible sharp objects. Ironically, the soft, fatty precursor of ambergris—which, unsurprisingly, starts out smelling like poop—hardens and darkens while floating at sea, ending up with a distinctive, musky smell long prized by perfumemakers. At current prices, a 1-kilogram sample can be worth $20,000 or more. (In most modern perfumes, however, the rare and fragrant substance has largely been replaced by synthetic materials.)

Because the fecal matter of dinosaurs and other ancient creatures has been found in the fossil record, ambergris should have been preserved, too, says Angela Baldanza, a sedimentary geologist at the University of Perugia in Italy. Yet no one had ever reported coming across it, she notes.

While Baldanza and her colleagues were on a geological survey in central Italy in September 2011, they discovered more than two dozen unusual lumps eroding from a layer of marine sediments. They seemed to be fossils, she notes, but they didn’t look like any trace fossils she’d ever seen. What they did look like were lumps of ambergris, so the team began a detailed analysis.

A variety of clues eventually led the researchers to identify the masses as fossilized ambergris, the researchers will report in a forthcoming print issue of Geology. First, Baldanza says, was their size and shape. The elongated lumps are 30 to 60 centimeters high and from 60 centimeters to 1.2 meters across, and each one has a tapered, grooved end. (In the two ambergris lumps found within modern-day sperm whales and described in detail, the tapered end pointed toward the whale’s anus and the larger, more rounded end pointed toward the whale’s stomach.) Second, several of the lumps contain fossilized squid beaks—remains of a modern-day sperm whale’s favorite prey. Third, chemical analyses of the rocks yielded eight amino acids consistent with those found in squid beaks, as well as substances produced only by a mammalian digestive tract. Finally, other fossils in the clay-rich sediments surrounding the lumps indicate that the materials were laid down on a sea floor no more than 150 meters deep about 1.75 million years ago, she notes. Sperm whales are known to have inhabited the Mediterranean at the time, Baldanza notes.

“With four lines of evidence, I think they’ve really nailed the interpretation” that this is fossilized ambergris, says Anthony Martin, an ichnologist (a specialist in trace fossils) at Emory University in Atlanta.

The team’s evidence is circumstantial but compelling, adds Nicholas Pyenson, a vertebrate paleontologist at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. “Is this fossil ambergris?” he asks. “They’ve made a pretty good case for it.”

“The geochemistry was what really [convinced] me,” says Andrew Rindsberg, an ichnologist at the University of West Alabama in Livingston.

Baldanza and her colleagues found 25 of the fossils in a region covering only 1200 square meters—an area a little smaller than three basketball courts. That leads them to suggest that the concentration of lumps may have come about when a large number of whales died and then sank to the sea floor, where the carcasses quickly decomposed in the warm, shallow waters but the ambergris—which on its own typically floats—was buried and preserved.

What may have killed so many whales all at once is a mystery, the researchers say, but causes could include disease, environmental stress, or even a mass stranding while chasing schools of squid into a freshwater bay.

The mass stranding interpretation is “speculative but plausible,” Martin says. One problem with that scenario, he notes, is explaining how the carcasses were transported from shore out to their final resting place but still remained close together.