Eran Sharon is a member of the nonlinear dynamics group at the Racah Institute of Physics at The Hebrew University of Jerusalem, where he received his Ph.D. in physics. His research interests include the spontaneous formation of structured fluid flows as well as the origins of mechanical instabilities and their role in the growth of plants. This article was developed from a talk Sharon delivered at the Kavli Institute of Theoretical Physics at the University of California, Santa Barbara. Address for Sharon: The Racah Institute of Physics, The Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904, Israel. Internet: erans@vms.huji.ac.il