“When they met, Sir David gave Prince George a tooth from a giant shark the scientific name of which is carcharocles megalodon (‘big tooth’),” the caption stated.
Speaking about the generous exchange to The Times, David later revealed why he gifted the 70-year-old object to the future King of England.
“When I was his age, I remember being given fossils by a grown-up, so I thought I would do the same," David told the British publication.
On Sunday, Wills and Kate revealed the filmmaker found the extremely old tooth fossil while holidaying in Malta with his family in the late 1960s.
“Sir David found the tooth on a family holiday to Malta in the late 1960s, embedded in the island’s soft yellow limestone which was laid down during the Miocene period some 23 million years ago.
“Carcharocles is believed to have grown to 15 metres in length, which is about twice the length of the Great White, the largest shark alive today,” the message stated.
David also recalled to the publication how the young prince had been extremely inquisitive about the object, asking lots of questions about its origin.
“ [George asked] What it was? How big it was? And so on,” David began.
“He was certainly very interested. He seemed to like it. He is very interested in fossils. She [Charlotte] was too. All three seemed charming," he added.
David’s candid confession comes after Wills and Kate showed their support for the iconic filmmaker’s conservation and environmental causes.
In addition to sharing several delightful new snaps of the meet and greet with Sir David, the Cambridges also revealed their own desire to "protect the natural world".
"With a shared passion for protecting the natural world, [Wills and David] continue to support one another in their missions to tackle some of the biggest environmental challenges our planet faces," the lengthy Instagram post stated.
"This includes working together on The @EarthshotPrize, the most prestigious global environment prize in history – further details of which will be shared in the coming weeks."