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.

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.

Nearly 2,000 years after a young man died in the Vesuvius volcanic eruption, scientists have discovered that his brain was preserved when it turned to glass in an extremely hot cloud of ash. Researchers found the glass in 2020 and speculated that it was a fossilised brain but did not know how it had formed.