One little girl in Maryland got a big surprise for Christmas, but it wasn’t under her tree – it was an ancient fossil hiding underwater. 

Alicia Bruce Sampson wrote on Facebook that her daughters Molly and Natalie asked for insulated waders for Christmas so that they could “go sharks tooth hunting like professionals.” And as soon as they got the waders, that was just what they did. 

Molly ended up with a massive and ancient surprise – a megalodon tooth as big as her hand.

“I’m pretty sure Molly is feeling like this is the best Christmas ever,” her mom wrote on Facebook. “… This tooth was in the water, so thanks to the waders she got the best part of her present!” 

The family took the tooth to the Calvert Marine Museum, which confirmed the fossil’s identity and shared the exciting news of the “future paleontologist” on Facebook. According to the museum, Molly had taken her find to their paleontology department, but still gets to keep it to enjoy for herself. 

In an interview with Newsweek, Sampson said that the tooth is five inches long and that her 9-year-old daughter found it along Calvert Beach, which sits along Chesapeake Bay. 

Stephen Godfrey, curator of paleontology at the Calvert Marine Museum, told CBS News that the tooth belonged to the Otodus megalodon, a now-extinct shark species that was “one of the largest, if not the largest marine macropredator the world has ever known.”

Specifically, the tooth is from the left side of the shark’s upper jaw, Godfrey said, which is known because of the width of the tooth’s root. Godfrey said the shark that would have had the tooth would likely have been between 45 and 50 feet long. 

“The massive root would have anchored this tooth firmly to the jaw, allowing megalodon the bite through any whale or dolphin it could catch,” Godfrey said. “We know that it was an active predator because from time to time we find fossilized whale and dolphin bones that preserve tooth gouge marks made by megalodon.” 

According to the Australian Museum, this species lived between 23 to 3.6 million years ago. They were known to grow to be more than 66 feet long, according to the museum – about three times the size of a great white. 

Last year, scientists were able to create the first 3-D model of the massive shark. Using it, researchers found that the megalodon was able to “cruise at faster absolute speeds than any shark species today and fully consume prey the size of modern apex predators.” The shark, they said, was a “transoceanic superpredator.” 

Molly’s discovery, Godfrey said, was a “once-in-a-lifetime kind of find.” 

“People should not get the impression that teeth like this one are common along Calvert Cliffs,” he said, adding that Molly found the tooth along a private beach. “…And she didn’t have to dig into the cliffs to find the tooth (which could be dangerous) it was out in the water. Her find is wonderful because she has an interest in paleontology and this will propel her and others her age to explore the sciences!”