Physicists have built a crystal out of an "einstein" tile — an elusive shape mathematicians spent years searching for — and found that it bends light in a way no ordinary crystal can. In the new study, published July 29 in the journal Nature Communications , researchers arranged this never-repeating tile shape into a pattern of nanoscale holes. This structure, known as a photonic crystal, is designed to control the way light moves through it. "I decided to include it in our photonic crystal structure," Moritake told Live Science, describing it as the starting point for the project. The holes were arranged according to the hat tile's pattern, covering a chip roughly half a millimeter across ‪—‬ about the width of a pencil tip.