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.

Mount Vesuvius was so hot it turned a man’s brain into glass when it erupted, fascinating new research shows. A piece of dark glass was found in the man’s skull, who died in the Roman city Herculaneum almost 2,000 years ago.

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.