On Christmas Eve, Isaac Jones went hiking with his new metal detector, on a trail by the Yuba River, near Nevada City, Calif. It was the first time he had ever used a metal detector, and at the beginning of his walk, he found the sort of small items that metal detectors most often pick up—coins, bits of metal trash and bullet shells, as the Union reports.

After hiking for about a mile, though, he came upon an unusual object. It was a human jawbone, buried in the ground. The metal detector had noticed the three gold teeth embedded in the bone.

The spot where Jones found the jawbone, known as Edward’s Crossing, was a toll road used by miners during the gold rush, when people would pan for gold in the river.

Local authorities will send the jawbone for testing to find out how old it is. It’s possible that it’s a century old, although could also have been buried more recently. “Maybe I can help a family get some closure or potentially help with an unsolved case,” Jones wrote on Facebook.