Researchers who examined the remains of a man whose brain was purported to have turned into glass when he was killed nearly 2,000 years ago in the volcanic eruption of Mount Vesuvius say they have

Fragments from the brain of a man killed by the Mount Vesuvius eruption in the year 79 are smooth and shiny but still contain visible neurons.

The research team used X-ray imaging and electron microscopy work out that the brain must have been heated to at least 510C before cooling rapidly. The pyroclastic flow is believed to have reached temperatures up to 465C, so the glass substance wouldn't have formed from this alone.