I was slightly shocked to see a slide of ‘fossilized brains’ from the Cambrian thrown up on a slide. Brains? From the Cambrian? Turns out I was right to be shocked. “People find it hard to swallow” says Nicholas Strausfield, a neuroanatomist from the University of Arizona. He was trawling through Burgess Shale fossils of Waptia – a small shrimp-like creature from the Cambrian – looking for hints of the evolutionary relationship between insects and crustaceans, when he found 3 samples that seemed to have brain-shapes in them. “I have flattened a lobster brain, and it looks like that,” he says. You can’t tell too much from these fossils, except that the brain was apparently big enough to handle some complex sensory information from the antenae and simple eyes.