After coal mine workers found the 50-pound specimen, paleontologists studied the site and uncovered more than 20 additional bones

Coal miners in North Dakota have uncovered a seven-foot-long, 50-pound mammoth tusk that’s been buried for thousands of years.

They found the fossilized specimen—which paleontologists estimate to be between 10,000 and 100,000 years old—while excavating an old streambed at the Freedom Mine near Beulah, North Dakota. The 45,000-acre surface mine, which is owned by North American Coal, is located near the center of the state.

Miners unearthed the tusk in May, according to a December announcement from the North Dakota Department of Natural Resources. Since then, paleontologists have been further exploring the site. They’ve found more than 20 additional mammoth bones so far, including parts of hips, ribs, a tooth and a shoulder blade.