A rare sequence of heating and cooling triggered the chain of chemical reactions that turn organic material into glass.

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,

The hard skull and spine of the man—whose remains archeologists found still in his bed in the town of Herculaneum—likely protected the brain from complete thermal breakdown, allowing fragments to form into organic glass.