Around the world, rare rock-like clumps have long washed ashore. Known as ambergris, the waxy substance is prized for its use in the perfume industry and treasured for its supposed medicinal purposes on black markets. Now, DNA analyses conducted by an international team of scientists confirm the icky origins of these intriguing lumps.

You may need to put your lunch down for this one: it's a blob formed in the digestive tract of sperm whales.

Ambergris, also known as jetsam, is found on beaches around the world and was thought to be a natural product of sperm whales. However, it has only been indirectly linked via similar, though unanalyzed, samples found in their guts. The masses are primarily composed of ambrein, alcohol that originates in the digestive tract of the sperm whale where it perhaps builds up into a dense, solid mass within the whale colon. Its makeup of varying characteristics – some are grainy while others are denser – makes it particularly capable of surviving extreme oceanic environments, with some samples estimated to be up to thousands, even millions, of years old.

“Jetsam ambergris has long been an enigmatic material, subject to discussion and analyses in scientific publications since the eighteenth century,” write the researchers in Biology Letters.

In order to understand where jetsam ambergris originates, researchers extracted and analyzed DNA sequences from three samples found in the North Sea as well as the Indian and Pacific Oceans. A fourth sample was taken from a sperm whale beached in The Netherlands in 2012, which provided “fresh” ambergris from a known origin for the researchers to compare. Phylogenetic analyses “unequivocally supported” that all four samples were derived from sperm whales (Physeter macrocephalus).

“While confirmation of a sperm whale origin for jetsam ambergris is not a surprising result, the present study is the first in providing a significant proof-of-concept in retrieving endogenous DNA from ambergris and successfully using it for organism identification,” write the study authors, adding that it is still possible that other closely related deep-diving whale species may also produce ambergris but have not yet been recorded doing so.

It could be that squid beaks found in an ambergris specimen irritate the whale to the point of throwing up, hence producing a highly valuable gastrointestinal byproduct. However, it's also possible it's condensed feces. The findings are the first to confirm the biological origin of jetsam ambergris through DNA analysis.

“These results demonstrate significant implications for elucidating the origins of jetsam ambergris as a prized natural product, and also for the understanding of sperm whale metabolism and diet, and the ecological mechanisms underlying these coproliths,” write the researchers.

Ambergris may also play a role in understanding the life history of sperm whales over long periods of time. The oldest known sample dates back to the Pleistocene era up to 2.5 million years ago, though it is unlikely DNA has been preserved so long.

“A great deal is still unknown about the ecology and adaptation of the marine giants formerly characterized as semi-mythical beasts, and ambergris may now prove a small but significant key to understanding some further aspects of them,” conclude the authors.