On the shores of the west coast of Australia lies a window to our past: the stromatolites and microbial mats of Gathaagudu (Shark Bay). To the untrained eye they look like a collection of rocks and slime – but they are in fact teeming with microbial life. And these stromatolites are living "relics" of ancient ecosystems that thrived on Earth billions of years ago. If you wade past, it feels like you're walking back through time. In fact, the first bubbles of oxygen that filled the atmosphere on