Fragments of papyrus PHerc. 1521, held by the British Library. Photographer unknown, British Library; source page, public domain.

The Herculaneum scrolls look like lumps of charcoal. Yet Greek writing remains inside those dark cylinders. The eruption of Vesuvius in AD 79 buried the town and the Villa of the Papyri, where an exceptional ancient library was found. The heat carbonized the scrolls: that transformation helped them survive, but also made them brittle and difficult to open.