Conservationists at Persepolis, Iran's most iconic ancient site, are waging a delicate battle against an unlikely adversary: tiny but persistent fungi eroding the millenia-old monuments. "In about 50, 100, or 200 years, they will turn the stone into soil, destroying the relief and the stone itself. If left unchecked, they will turn it into a ruin," explains Shahram Rahbar, head of renovation at the site, where he and his team are working relentlessly to combat the infestation. IMAGES AND SOUNDBITES