In a nutshell Scientists discovered a human brain from 79 CE Vesuvius eruption transformed into glass—the only known case of natural organic glass preservation in history. The brain vitrified at temperatures above 510°C followed by extremely rapid cooling,

It was a surprising discovery when scientists examining the remains of a man who died in bed in the ancient city of Herculaneum after Italy's Mount Vesuvius erupted in 79 AD found dark fragments resembling obsidian inside his skull.

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.