In 1993, cave explorers entered a long, narrow tunnel at the Lamalunga Cave near the town of Altamura in southern Italy. At the far end, they found an upside-down human skull fused into the rock alongside a large collection of other human bones.
The skull’s jutting brow was covered in a layer of pearl-like coralloid, calcium deposits otherwise known as cave popcorn. Much of the remains were covered in some form of the mineral that had leached down from the surrounding limestone.
Today, scientists believe the person (the “Altamura Man”) had fallen through a sinkhole in the surrounding limestone karst and never made it back out again. He starved to death, and the calcium deposits, along with stalactites and stalagmites, had sealed him into a calcified tomb.