WOMAN LOOKING FOR ENDANGERED FROGS FINDS A PERFECT 10,000-YEAR-OLD MASTODON TOOTH STARING AT HER

Brigid Lynch, a geomorphologist with Balance Hydrologics, was walking a wooded creek in the Santa Cruz Mountains for a habitat project meant to help the threatened California red-legged frog. She saw something in the water that did not match the rocks she'd spent all day looking at. Her own description of the discovery process: it was sitting in the middle of the creek, half in and half out of the water. She has joked that it wasn't hard to find. Ten thousand years of erosion, earthquakes and Bay Area real estate development, and the thing just laid there waiting for somebody with a clipboard. It's an intact molar from an adult Pacific mastodon, roughly nine inches long, crown and root both intact. Stanford curator Chrissy Garcia says you can see the root canal. Paleontologist Wayne Thompson called the tooth immaculate, the most complete mastodon molar from the area and the most spectacular he's ever seen, and said he got chills and shivers up and down his spine. That is a man who looks at old teeth professionally, soaking himself over a molar. The tooth went to Stanford's Doerr School of Sustainability for carbon dating and a 3D scan. Midpen gets a replica for public education, so eventually some eight-year-old will hold a plastic copy of the best fossil the Peninsula has ever coughed up.

Why you should give a shit: A project to save one threatened frog accidentally produced the finest mastodon molar in the region, which is the actual argument for leaving 70,000 acres of hills alone: nobody ever found the Ice Age under a parking structure.