An ancient tooth belonging to one of the largest sharks ever to roam the ocean has gone missing from a secret location on the remote Ningaloo Coast World Heritage area of Western Australia.

Wildlife officers and police are investigating the disappearance of the Megalodon tooth, which could be worth thousands of dollars to collectors.

The empty space where the ancient fossil once sat. ( Supplied: Robbie Bullen )

Arvid Hogstrom from Parks and Wildlife in Western Australia said the fossilised tooth had been unearthed in the Cape Range National Park, with its precise location kept under wraps.

"It was definitely a secret," Mr Hogstrom said.

"There was only a few key local people who actually knew where it was.

"But it only takes one person to tell the wrong person and we end up where we are now.

"It could be someone who doesn't know what they've taken. It could be an amateur collector who wants to add to their collection, or it could be someone who wants to trade it on the black market."

No 'bulletproof' shark tooth cage

Mr Hogstrom said his team had been working on protecting the fossil.

"We've been looking at everything from bulletproof glass covers and other sorts of cages to enclose it," Mr Hogstrom said.

"But obviously someone's got in there before we've been able to [secure it]," he said.

"There's another [Megalodon tooth] that is quite well known, and a lot of tour companies and buses go in there and have a look at it.

"Whereas this one was specifically hidden away because we realised it was a better specimen and we were looking at ways of protecting it."

Giant shark extinct for 1.6 million years

Megalodon grew to more than 15 metres long and weighed around 20 tonnes, about three times as heavy as a Tyrannosaurus rex.

Mr Hogstrom said it is believed that the ancient shark species became extinct at least 1.6 million years ago.

An artist's impression of the now-extinct megalodon shark, which was an incredible 15 metres long. ( Supplied: CSIRO )

"The tooth has been floating around on the seafloor for quite some time. It's been pushed up into the ranges and was sitting there undisturbed for however long," he said.

"Now someone's come along with a bit of a chisel and simply taken it away."