Scientists have used microscopic fossils to precisely date Victoria's Twelve Apostles (the famous sea stack formations along Australia's Great Ocean Road, south-west of Melbourne) at between 8.6 and 14 million years old, according to research published in the Australian Journal of Earth Sciences. Researchers analysed tiny single-celled organisms called foraminifera — which evolved and went extinct at known points in time — embedded in the site's Port Campbell limestone to establish the age of each rock layer, formed during a period of major global cooling now known as the Middle Miocene Climatic Transition. Experts say the findings are significant because, despite more than a century of geological study, they reveal how much remains to be learned about even the world's most visited and recognised natural landmarks.