In nature,technology and art the most common form of regularity is repetition: a single element repeated many times, as on a tile floor. But another form is possible, in which smaller and smaller copies of a pattern are successively nested inside each other, so that the same intricate shapes appear no matter how much you "zoom in" to the whole. Fern leaves and Romanesco broccoli are two examples from nature.

One might have thought that such a simple and fundamental form of regularity...