Researchers found a tiny bottle from ancient Rome that contained fecal residue and traces of aromatics, offering evidence that poop was used medicinally more than 2,000 years ago.

Now, in research published in the Journal of Archaeological Science: Reports, researchers describe chemical evidence of a medicinal recipe penned more than 2 millennia ago by Galen, the famous Greek physician of ancient Rome. It involves a blend of human feces and fragrance. Such an arresting combination mirrored Galen’s instructions for masking the odors of certain foul-smelling medicines.

“It was a remarkable moment of interdisciplinary work,” says Rana Çelebi, a medical historian at Istanbul Medipol University who contributed to the research, “to produce a uniquely tangible window into the ancient medical practice.”

Medicinal poop isn’t just a thing of the past. Some modern physicians have started using it as a kind of gut microbiome reset for those struggling with a debilitating kind of GI infection caused by the bacterium Clostridium difficile, and are researching it for other uses. Rather than mixing it with aromatics to make it more palatabl