Pompeii - this is actually a cast of the void left by a person who was unfortunately in the wrong place at the wrong time when Mt. Vesuvius erupted that fateful day... Horrifying, and I cannot imagine the terror.
The victims of Pompeii's volcano's victims. When the ash poured down over the city, people were killed instantly, in the exact poses they struck when they noticed their impending doom. As their bodies decomposed, they left perfectly-formed hollows in the ash. Historians can inject these hollows with plaster, recreating the positions of the bodies, and sometimes their terrified facial expressions.