During the last Ice Age, a person living along the Rhine River in what is now Europe picked up a piece of rock and etched the image of what appears to be a fish caught in some netting. They wouldn’t have guessed that 15,800 years later, researchers would declare their etching as one of the earliest depictions of fishing in human history. Researchers from Durham University in England and the Leibniz Zentrum für Archäologie in Germany used advanced imaging techniques to reveal a fish engraving behind grid-like patterns on an ancient schist plaquette (a small slice-like piece of a type of metamorphic rock).

As the researchers detail in their study, published earlier this month in PLOS ONE, the grid patterns can be interpreted as representing fishing nets or traps, making this artifact not only the oldest depiction of fishing in European prehistory, but also the only material evidence of how Paleolithic hunter-gatherers from this period caught fish. Of course, that’s if the researchers’ interpretation is accurate. “Although it is known that fish formed part of the diet of Paleolithic hunter-gatherers at the time, until now, no evidence existed as to how fish were caught,” the researchers explained in a Leibniz-Zentrum für Archäologie statement .

This latest find is one of hundreds of engraved plaquettes archaeologists have recovered from Gönnersdorf, an Ice Age campsite in modern-day Germany inhabited by hunter-gatherers about 15,800 years ago. In addition to .