Recent storms and high tides have unearthed a prehistoric marvel on the coast of North Carolina.
Fossilized shark teeth, some as big as an adult hand, have been plucked from the sand by beachgoers in North Topsail Beach and Surf City, North Carolina, NBC-affiliate WITN first reported.
The teeth are immense and immensely old: Researchers say the teeth once belonged to a Megalodon, the largest shark ever to live. Megalodon went extinct some 2.6 million years ago.
Experts at the Aurora Fossil Museum in Aurora, North Carolina told WITN that a comparison of modern sharks' teeth and those recently collected allows them to estimate that every inch of a fossilized tooth equals about ten feet in shark. Therefore, they say a six-inch long tooth belonged to a Megalodon that was about 60 feet long.
That estimate tracks with a 2013 study that put the Megalodon at a maximum length of 59 feet, about three times the size of an average great white, a distant ancestor of the prehistoric predator.
The study concluded the mega-shark grew bigger and bigger over a 14-million year evolutionary span, though researchers are still unclear why the shark continued to grow.
"Perhaps something was going on with the productivity and climate that produced that pattern, or with their prey and their competitors that made the species become large," co-author large," Catalina Pimiento from the University of Florida and the Smithsonian Tropical Research Institute in Panama said at the time her research was released.
Megalodon may have been more vulnerable to extinction due to its size, but while it prowled the oceans it was incredibly strong: its jaw was three times stronger than that of a Tyrannosaurus rex.
It was only relatively recently – a few hundred years ago – that humans have even known what they are looking at when shark teeth come ashore.
According to Discovery's Sharkopedia, Megalodon fossils were often mistaken for moon rocks that had fallen to Earth, or the ancient tongues of dragons or giant serpents.
Then in 1666 while studying "tongue stones" found embedded in rocks throughout Europe, naturalist Nicolas Steno noted that they were in fact shark's teeth. Steno, one of the founding figures of geology, was among the first to realize that fossils represented organic remains.
The North Carolina coast is a well-known trove for fossilized teeth from the Megalodon, according to experts.
[Editor's note: An earlier version overstated the rarity of Megalodon teeth.]