NARRAGANSETT, R.I. (WPRI) — What began as a typical beach day turned into an unforgettable experience for 6-year-old Oliver Martinez, who dreams of becoming a paleontologist.

"I was surprised and I just couldn't believe that I found it," Oliver told 12 News.

The Martinez family from South Kingstown was collecting seashells at Narragansett Town Beach on a summer Sunday in July when Oliver stumbled upon something extraordinary.

"It was on the ground. I picked it up and then I showed it to my dad," he said.

"I thought his dad was pulling a joke on us," his mom, Lauren Martinez, recalled. "I couldn't believe it."

But it wasn't a beautiful conch shell or a giant sea creature.

Oliver had discovered a fossilized shark tooth—one that experts believe could be anywhere from thousands to millions of years old.

After seeing the size of the fossil in her son's hand, she decided to ask scientists at the University of Rhode Island and the Atlantic Shark Institute where it came from. They identified it as a white shark tooth, based on its size and shape.

"They told us that because those sharks lived in this area in a certain era, it was likely to be between six million and ten million years old," Lauren said.

Jon Dodd, executive director of the Atlantic Shark Institute, told 12 News that this is an incredibly rare find.

"Really, really unique to find any shark tooth, to find that shark tooth," Dodd said. "That's one in a million."

It’s safe to say the Martinez family now has a new family heirloom, as Oliver has already placed the ancient tooth in its own special case.

"I don't know how we'll top this in any other summer," Lauren said.