For billions of years, microbes like bacteria have quietly transformed the Earth. They have re-routed the flow of nutrients around our planet, infused the atmosphere with oxygen, and built the biosphere from the bottom up. It is hard to overstate the palaeontological importance of “simple” single-celled micro-organisms. Unfortunately for palaeontologists, however, these small, soft, delicate…

Fossils provide our most decisive evidence for testing hypotheses about the abundance, diversity, and evolution of life on Earth over the past three-and-a-half billion years. They are also our best hope for answering one of the most compelling questions in science: was there ever life on Mars?