A six-year-old boy looking for shells on a beach has found a rare megalodon tooth dating back some three million years.

Sammy Shelton, from Bradwell, near Gorleston, was with his dad Peter on Bawdsey Beach, in Suffolk, at the weekend when he made the exciting discovery.

Mr Shelton, a retired GP, said the pair had been scanning the shoreline for shells and sharks' teeth when they found the tooth, a fossil relic of the largest shark that ever existed - an apex predator which specialised in killing whales.

He said other people on the beach - which is popular with serious fossil hunters with trowels and kneeling pads - were able to tell them how rare and significant it really was.

"We knew what it was but not how rare it was," he said.

"One of the chaps seemed to be an authority and said he had been looking for fossils for years and years and never found one of that size and complete.

"Now that Sammy has found this it has really piqued his interest and he took it to school to show his class."

Evolutionary biologist, broadcaster, and author professor Ben Garrod shared his excitement over Sammy's "amazing" find which would be of interest nationally with only one or two found on British shores every year.

He said the "once-in-a lifetime" find was "a really lovely discovery" adding the enamel and root were still visible.

"I have looked for one since I was Sammy's age and never found one," he said.

"They are found all over the world but we do not often find them in the UK, just a couple a year.

"It is a really unusual discovery and usually they are much more heavily eroded than this one. It's a really nice one for a British one."

He said the megalodon (meaning large tooth) was the largest shark that ever existed - at least three times bigger than a great white - swimming around the oceans until around three million years ago.

"This little boy is the first person to touch this in nearly three million years," he said.

"He is handling the tooth of the largest ever predatory shark and one that will be of interest to the whole palaeontology community."

Move over Jaws

Megalodon was the largest fish that ever lived and with a mouth nearly 10ft wide full of 276 teeth it may have had the most powerful bite of all time.

Even though megalodons and dinosaurs are both extinct, they never coexisted. The dinosaurs died out about 66 million years ago. Megalodons came later the oldest fossils dating from 23 million years ago.

Fossil remains of the megalodon have been found off the coast of every continent except Antarctica.

Since sharks don't have bones, most of what we know about megalodon comes from its large fossil teeth - getting through up to 40,000 in its lifetime with a set shed once every one to two weeks.

The largest megalodon tooth ever found was 6.9 inches long - almost three times longer than the average tooth of a modern great white shark.

Great Yarmouth's Jason Statham starred in American science fiction movie The Meg about a megalodon which attacks Pacific Ocean deep sea adventurers.