Over half a billion years ago life on Earth took an incredible step in evolution, when animals learned to build skeletons. Using many different materials, from calcium carbonate and phosphate, and even silica, to make shell and bone, they started creating the support structures that are now critical to most living forms, providing rigidity and strength. The Leicester University palaeobiologist explores the incredible variety of the skeleton innovations that have enabled life to expand into a wide range of niches and lifestyles on the planet. Discussing the impact of climate change, which puts the formation of some kinds of skeleton at risk, he also considers future skeletons – including the possibility that we might increasingly incorporate metal and plastic elements into our own – as well as the possible materials for skeleton building on other planets.