A researcher surveying a San Mateo County creek for a frog habitat stumbled upon a remarkably preserved Pacific mastodon molar, a rare Ice Age relic estimated to be at least 10,000 years old. Paleontologists confirmed it was an intact molar from an adult Pacific mastodon. The tooth is about 8.5 inches long, 7 inches deep and 3 inches wide.

A fossilized Pacific mastodon tooth believed to be at least 10,000 years old was found in “immaculate condition” in a California creek bed, according to local officials.

A routine field survey in a California redwood forest has led to an extraordinary glimpse into the Ice Age. A scientist searching a San Mateo County creek for signs of habitat…