A small robot that can shape-shift and produce heat could incinerate cancer cells or stop bleeding from inside the body. It could also be used to ferry drugs directly to tumours or hard-to-reach places like arteries. Tiny robots with soft bodies have shown promise for delivering drugs without causing damage – but adding hard elements could make them more useful. Ren Hao Soon at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, and his colleagues designed the centimetre-sized robot to have overlapping aluminium plates inspired by pangolins, the only mammal with scales. They layered rectangular "scales" over softer, magnetic material, which let the robot change its shape.