Conservationists at Persepolis, Iran’s most iconic ancient site, are waging a delicate battle against an unlikely adversary: tiny but persistent lichens eroding the millennia-old monuments. Conservationists at Persepolis, Iran’s most iconic ancient site, are waging a delicate battle against an unlikely adversary: tiny but persistent lichens eroding the millennia-old monuments. Archaeology Phys.org – latest science and technology news stories