Desert-loving fungi and lichens pose deadly threat to 5,000-year-old rock art

The Negev desert of southern Israel is renowned for its unique rock art. Since at least the third millennium BCE, the hunters, shepherds, and merchants who roamed the Negev have left thousands of carvings (petroglyphs) on the rocks. These figures are mostly cut into desert varnish: a thin black coating on limestone rock, which forms naturally. Many represent animals such as ibexes, goats, horses, donkeys, and domestic camels, but abstract forms also occur.