Genes determine how plant cells grow and divide, shaping for instance tomatoes to be pear-like or spherical. But many fruits and ‘vegetables’ are round because the form appears to offer key advantages. One is that mathematically, a ball combines the maximum volume with the minimum peel. Spheres also withstand impact well when they fall, and roll farther to spread seeds. Their shape may also help attract animals, which can help with dispersal. So it’s no surprise that in nature, the shape occurs again and again.