The crystal symmetry that was called impossible

Chemistry textbooks used to treat crystal structures like a rigid religious dogma, insisting they could only repeat in very specific ways. When Dan Shechtman found a crystal with a mathematically 'forbidden' five-fold symmetry under an electron microscope, his research group literally kicked him out for being crazy. He had the last laugh decades later when his discovery of 'quasicrystals' won him a Nobel Prize.