Related Program: NPR's Morning Edition Student Discovers Mastodon Tooth In His Backyard By editor • May 17, 2012 Related Program: NPR's Morning Edition TweetShareGoogle+Email Listen Listening... / An Oklahoma teacher asked her fifth graders to each bring in a rock. One student brought in a stone that looked like a tooth. It turns out it was a tooth, according to the Muskogee Daily Phoenix. The tooth may up to 40 million years old. TweetShareGoogle+EmailView the discussion thread.