Geologists say that they have unearthed some of the oldest known evidence for life on Earth. The discovery, yet to be confirmed, suggests that life arose quickly on the young planet. In this week's Nature, Australian and British researchers report finding layered structures called stromatolites in 3.7-billion-year-old rocks from Greenland. Stromatolites, which look a bit like geological cauliflowers, form when microbes trap sediment and build up layer after dome-shaped layer.
Image: Scientists have found evidence of stromatolites much like these in Shark Bay, Australia within 3.7-billion-year-old rocks from Greenland. Credit: PAUL HARRISON Wikimedia Commons
