But that's exactly what happened late last summer when Phillip Stoll was exploring the creek behind his home in Ingham County's Windsor Township with a friend and stepped on something sharp.
Known as "Huckleberry Phil" in the neighborhood for his love of exploring the creek barefoot, the 9-year-old was walking with a friend through the creek when his foot felt something out of the ordinary.
"It felt weird," he said. "I had to see what it was. I pulled it out and brought it to my mom."
Mom Heidi Stoll was working on the computer when he brought it in and immediately thought it was some kind of old car part or misshapen rock.
"I didn't even think that it could have been a tooth until I started checking online for some kind of match," she said. "We saw a picture of a mastodon tooth and said 'there it is.'"
The family eventually emailed a photo of the tooth to Jim Harding, a Michigan State University Herpetologist and Wildlife Outreach Specialist for the Department of Zoology and MSU Museum.
Harding confirmed the find recently, and said the tooth was the top portion, which probably broke off at some point.
"These were elephant-sized beasts that roamed through Michigan over 10,000 years ago," he said. "They would look like a hairy elephant if you saw one today."
He said people find mastodon bones every three to four years in Michigan. Two young boys made national news when they found a mastodon axis bone while fishing in Shelby Township in 2012.
As far as the Lansing area, there were some bones found in Williamston and Fowlerville years ago, he said.
"It is a great reminder of what used to roam the country," he said. "It most likely got stuck in a swampy area and drowned."
Harding said the tooth most likely slowly drew to the surface as the banks of the creek eroded. He said there may even be more parts out there deeper in the ground.
The tooth has become part of a lesson at the Stoll household. Heidi home schools Phillip's six siblings and now uses it to teach them about the creatures.
"It's really neat how it looks like a giant tooth," Phillip said. "It was fun trying to figure out what it was. My mom was surprised."