In 1931, researchers working in southern France unearthed a large seashell at the entrance to a cave. Unremarkable at first glance, it languished for decades in a natural history museum.

Now, a team has reanalyzed the roughly foot-long conch shell using modern imaging technology. They concluded that the shell had been deliberately chipped and punctured to turn it into a musical instrument. It's an extremely rare example of a "seashell horn" from the Paleolithic period, the team concluded. And it still works — a musician recently coaxed three notes from the 17,000-year-old shell.

"I needed a lot of air to maintain the sound," said Jean-Michel Court, who performed the demonstration and is also a musicologist at the University of Toulouse.

The Marsoulas Cave, in the foothills of the French Pyrenees, has long fascinated researchers with its colorful paintings of bison, horses and humans. It's where the enormous conch shell was discovered, which must have been transported from the Atlantic Ocean, more than 150 miles away.

Presumed to be nothing more than a drinking vessel, the shell from the sea snail Charonia lampas sat for more than 80 years in the Natural History Museum of Toulouse.

Only in 2016 did researchers begin to analyze the shell anew. Artifacts like this conch help paint a picture of how cave dwellers lived, said Carole Fritz, an archaeologist at the University of Toulouse who has been studying the cave and its paintings for over 20 years.

Fritz and her colleagues assembled a three-dimensional digital model of the conch, and used CT scans and a tiny medical camera to examine the inside of the conch. They found a hole, roughly half an inch in diameter, that ran inward from the broken apex and pierced the shell's interior structure.

The smoothed outer lip would have made the conch easier to hold, and the broken apex and adjacent hole would have allowed a mouthpiece — possibly the hollow bone of a bird — to be inserted into the shell. The result was a musical instrument, the team said. This shell might have been played during ceremonies or used to summon gatherings, said Julien Tardieu, another Toulouse researcher who studies sound perception. Cave settings tend to amplify sound, Tardieu said. "Playing this conch in a cave could be very loud and impressive."