On August 24, 79 AD, Mt. Vesuvius in Pompeii, Italy exploded in a volcanic eruption. Tons of molten ash, pumice and sulphuric gas went miles into the atmosphere. In the 1800's, Archaeologist's were able to make casts of the bodies from the victims by filling the cavity with liquid plaster then carefully chipping away the lava, eventually to reveal a perfect cast of the body.
VII.16.17-22 Pompeii. December 2007. Plaster cast of body lying at foot of staircase. Four people met their death in this house, three of them died huddled together on this staircase. They were discovered in November 1961. It was possible to make casts of the group of three. The lowest of the three bodies remains where it was discovered. The fourth skeleton was lying on the landing at the bottom of the stairs but only a photo remains of this skeleton.
Herculaneum, Pompeii sister city, also buried in the eruption. Was hermetically sealed by the ash and lava so many items such as bone and wood were preserved, which was not the case with Pompeii. However, there is a modern city above herculaneum, so only about 25% has been excavated.