The eruption of Mount Vesuvius 2,000 years ago turned a victim’s brain tissue into glass. Scientists say they have figured out how this unusual phenomenon occurred.

The eruption of Mount Vesuvius in 79 CE presented its surrounding ancient Roman communities with a number of terrifying ways to die: falling debris, collapsing buildings, asphyxiation from superheated dust plumes,

A fast-moving current of hot gas and volcanic matter, also called a pyroclastic flow, followed, burying the area. Experts believe the ash cloud turned the man's brain into glass because the pyroclastic flow would not have reached high enough temperatures or cooled quickly enough.