Enlarge Image Old stomping grounds. This landscape in Western Australia is home to these very ancient fossil cells (inset). Credit: David Wacey/University of Western Australia When Martin Brasier discovered what looked like fossil cells in between the cemented sand grains of an ancient beach in Western Australia, he knew he had his work cut out for him. One of the biggest challenges for geologists is deciding when a fossil is really a fossil, particularly when it comes to early life. There are no bones to go by, and the mineralized spheres representing simple cells and sometimes filaments could easily...