Researchers investigating a vulture nest in a cliff cave in southern Spain discovered an unusual piece of footwear — a grass shoe from medieval times. Further investigation of neighboring roosts revealed that generations of vultures had feathered their nests with other historical artifacts, including pieces of leather, cloth and string.
"The good conditions of the caves have allowed the artifacts to be preserved for centuries, suggesting that these nests are authentic natural museums," study co-author Antoni Margalida, an ecologist at the Pyrenean Institute of Ecology (CSIC) in Spain, told Live Science in an email.
