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.

Researchers found organic glass in the skull of a volcano victim, indicating the extreme and unique environment triggered by Vesuvius's eruption in 79 CE.

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.