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JAMESON, Mo. – A day of exploring led to the finding of a priceless fossil for one 18-year-old.

Ira Johnson of Jameson, Missouri found the tooth of a mastodon in the Grand River on August 29.

Johnson told’s Monica Ryan that he goes exploring often and was introduced to it by his father and uncle. He said he started the hobby when he was about 5 or 6 years old.

“I usually find silver-plated spoons or just a bunch of junk really,” Johnson said. “When I was in there looking and I walked over to the water’s edge and I saw the tooth and I didn’t really think much about it because it looked just like a normal rock.”

Johnson’s father usually looks for arrowheads and coins and is a seasoned explorer so when Johnson got home and showed his father his new treasure, his father’s “face brightened” signaling that Johnson had found something extra special.

The tooth is about the size of Johnson’s hand and it was confirmed by professors at the University of Iowa that it is in fact the tooth of a mastodon that lived in America during the Pleistocene Epoch over 13,000 years ago. According to the San Diego Natural History Museum, mastodons diverged from other elephant-like animals.

Johnson’s plan for next summer is to get a kayak and float down from one bridge to the next and see if he can find anything else.