A baby ocellated lizard (top) and an adult one (bottom). Image reprinted by permission from Macmillan Publishers Ltd: Nature (doi:10.1038/nature22031), copyright (2017)

The ocellated lizard is a beautiful creature. When it's young it's brown with white dots, but as it gets older its scales become black and green. Individual scales continue to switch colour, until the simple polka dot pattern turns into an intricate black-and-green labyrinth. It's an amazing transition — but how does the lizard do it?

The answer comes from some straight-forward maths involving something called a cellular automaton. To find out how this works, read Spotting lizards.

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