A fossilised tooth from one of the world's largest predators has been taken from the World Heritage listed Ningaloo Coast of Western Australia.
It is the latest in a string of incidents that has triggered an outcry from scientists as well as conservationist Tim Winton.
Winton, a writer and longtime advocate for the North West Cape, said the incident pointed to a pattern of disrespect for "one of the last wild places on Earth".
Authorities became aware of the missing tooth in the first week of August. (Supplied: DBCA)
The Department of Biodiversity, Conservation, and Attractions (DBCA) confirmed the megalodon tooth disappeared from the Cape Range National Park, about 1,300 kilometres north of Perth, early this month.
"Signs suggest it has been physically removed by someone with a potential chipping device," a DBCA spokesperson said.
In 2018, a specimen was removed from a secret site in the same national park and has never been recovered.
The site of a stolen megalodon tooth in Cape Range National Park near Exmouth. (ABC Pilbara: Alistair Bates)
Winton said the news of the latest disappearance was unsurprising.
"People [are] chiselling out fossil teeth, you know, going into caves that they know they're not supposed to, camping wherever they want, driving their troopies wherever they want," he said.
"I've picked up enough human excrement at Ningaloo in the past couple of years to know that this is not an imagined problem."
A cave featured in the ABC documentary series Ningaloo Nyinggulu, which was hosted by Winton, was recently gated to public access after researchers discovered extensive damage by illegal trespassers.
"I don't know if it's just Insta-bogans but … they bring everything up to Ningaloo except their good sense and their manners," Winton said.
The remains of an ancient sea bed thrust upwards by tectonic movement forms the Cape Range. (Supplied)
Fuel for the fossil black market
The megalodon, literally meaning "large tooth", was a giant prehistoric shark measuring up to 18 metres long and weighing up to 50 tonnes.
The abundance of teeth found in the Cape Range National Park has led palaeontologists to believe it was once a feeding ground.
Darren Brooks has explored the caves throughout the Cape Range for 35 years, assisting several research expeditions.
Mr Brooks said megalodon teeth could be priced at thousands of dollars, but more often than not the teeth were worth very little.
"A lot of people don't understand how large the fossil trade is and megalodon teeth are not particularly a valuable item," he said.
"You can buy them online quite cheaply, unfortunately."
Historical specimens of megalodon teeth are displayed at the park's visitor centre. (ABC Pilbara: Alistair Bates)
The removal of the teeth renders them useless to researchers.
"All these teeth that are on the market, people think they're great scientific value objects—they've [actually] lost all their value because they've been removed from the context of where they were deposited," Mr Brooks said.
Globally unique cave sealed
Conservationists are also concerned about damage being done to a scientifically significant cave in the Cape Range National Park, which is off limits to the public.
ABC documentary crews gained DBCA permits to film in the cave by implementing special techniques to minimise any disturbance.
But intruders entering illegally are wrecking its delicate subterranean environment, Mr Brooks explained.
Speleologist Darren Brooks said root mats have been destroyed by intruders in a secret cave. (Supplied: Darren Brooks)
He said a fig tree at the cave's entrance had especially suffered since its location spread among travellers.
"People go through in there and they're tearing down root mats out of the water-filled sections of the cave," he said.
"They're pulling aerial root mats down off the ceiling.
"And, of course, they're also vandalising by carving initials and stuff into the trunk with a tree."
An ancient fig tree covers the entrance to the cave, which contains rare albino fish. (Supplied: Darren Brooks)
Troglobite species which researchers believe may only exist within the cave are also under threat.
The WA Speleological Group raised the matter with the DBCA, and a gate has been installed to seal the cave's lower entrance.
'An Instagram trail'
Tens of thousands visit the park each year and both Mr Brooks and Winton fear the accelerating "exploitation" of the Ningaloo Coast since the COVID-19 pandemic.
The entry sign at the Cape Range National Park. (ABC News: Alistair Bates)
"A few places at Ningaloo [have] just become part of ... an Instagram trail," Winton said.
"It's just about people who think they are better than everybody else, and the rules don't apply to them.
"Our children have a lesser chance of experiencing the glories that we've been able to experience."
Tim Winton climbs down into a cave while filming the Ningaloo Nyinggulu documentary series. (Supplied: Artemis Media)
Winton acknowledged his Ningaloo Nyinggulu series has increased attention on the region, but said it was done to help protect the area.
"You can [either] not make documentaries, or you can make documentaries," he said.
"People either listen to the rules or they don't.
"The best thing to do is to make sure that we're all living up to our obligations as stewards of this place, and calling out bad behaviour when we see it."
The DBCA said in a statement it has increased efforts to protect the Cape Range National Park, such as more regular patrols and communication with the public.