In 2021, archaeologists working at an ancient site called Gre Filla in southeastern Anatolia in Turkey unearthed an amorphous, glasslike lump with a greenish yellow sheen and a ruddy bottom. Weighing about half a kilogram, it looked like it had melted on one side. The researchers recognized it as a partially melted hunk of soil and copper.

The region was a well-known hotbed of early metalworking around the sixth millennium B.C.E., after the first cities and towns emerged. But the lump, described last week in the Journal of Archaeological Science: Reports, was found in a layer of sediment that could be up to 10,800 years old. The date has raised eyebrows. If further work confirms the metal was smelted—the heating process by which metals get extracted from ore—it would mean hunter-gatherers there were experimenting with metallurgy thousands of years earlier than previously thought.