Folded Goursat surface and banana-shaped seedpod
  Thin vegetal shells have recently been a significant source of inspiration for the de\text{sign} of smart materials and soft actuators. Herein is presented a novel analytical family of isometric deformations with folds, inspired by a banana-shaped seedpod, which converts a vertical closing into either an horizontal closing or an opening depending on the location of the fold. Similarly to the seedpod, optimum shapes for opening ease are the most elongated ones. 
Etienne Couturier
cond-mat.soft