When archaeologists first found skeletons at Pompeii, they noticed that there was a gap between each skeleton and the hardened layer of ash around it.

The reason for this was that the ash had cooled and hardened around the body. Over time the flesh rotted away, leaving only the bones.

They drilled through the ash, and poured plaster into into the spaces around the skeleton. They let the plaster harden, then carefully chipped away the hardened ash around it, leaving casts of the victims at their time of death.