Living matter transforms energy stored at the molecular scale into the ability to grow, move, divide, and respond to its environment. Perhaps the most striking manifestation of these shape-changing powers is morphogenesis, through which a single nucleus transforms into an entire organism. While the field of developmental biology has enjoyed incredible success in understanding how these transformations depend on genetic ingredients, the physical processes involved have largely remained elusive. How does living matter sculpt itself into complex shapes? We will discuss some recent developments in this area and a particular instance of dramatic shape change in the development of an internal organ.