A fossil hunter from New Zealand has uncovered the remains of a 12-million-year-old dolphin encased in a large rock.

Mamlambo found the rock on a beach with bones clearly visible sticking out of it and so took it home to reveal what creature lay inside.

He used a kind of mini-jackhammer called an airscribe to chip away at the outer layers of rock and then placed the fossil in acid to eventually reveal the remains of the ancient marine creature.

"Four of the vertebrae are still in place (articulated) and one shows a potential bite mark from another animal, probably a large shark," he said.

This fossil will now be donated to a local museum, he said.

The edited footage was completed on April 6.

Mamlambo, from the YouTube channel Mamlambo Fossils, found a rock on the beach displaying a number of fossils bones sticking out of the matrix. This type of rock is called a concretion and is formed out of calcium carbonate. He took it home and use an air scribe to remove the bulk of the rock. An air scribe is like a mini jackhammer that chips the rock away. The fossil is termed "sticky" as the rock didn't flake away easily from the bone, to remove this last layer of rock without damaging the bone, acetic acid (vinegar) is used to dissolve the calcium carbonate in the rock.

After 12 hours in the acid, it spends 24 hours or more in fresh water that gets changed out a couple of times. This removes any acid before the newly exposed bone is consolidated. (01:05)

The exposed bone has to be protected from the acid by covering it in a thin layer of B72 which is a liquid that hardens into a layer of plastic when it dries (01:24). It first needs to dry before this can be done which is what happens in the time lapse at 01:15.

After a few rounds of air scribe and acid work, the bones are exposed enough to figure out that this fossil are the remains of an ancient dolphin. Four of the vertebrae are still in place (articulated) and one shows a potential bite mark from another animal, probably a large shark. The shark would have been feeding on the dead dolphin or potentially even killed it. The bite mark is shown inside the rectangle at 02:55.

The last step is called landscaping, where a dremel is used to remove the air scribe marks to make it more aesthetically pleasing.

This fossil will now be donated to a local museum.

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