Daily briefing: Tiny fossil has the oldest known rear-end

Nature, Published online: 24 March 2020; doi:10.1038/d41586-020-00891-y

A fossil the size of a grain of rice appears to be the earliest known bilaterian, the group of animals (including humans) with two-sided symmetry, two openings and a through-gut. Plus: the diagnostic tests for coronavirus available now and in the works, and two approaches to solving the global challenge of climate change.