The nanoscale structures on a gecko's foot enable it to cling to most surfaces. This scanning electron microscope image shows multiwalled carbon nanotubes attached to a polymer backing, an experiment designed to replicate the gecko foot's adhesive properties. The gecko's amazing ability to cling to vertical or inverted surfaces is due to the interaction between nanoscale structures on its feet and tiny crevices on the wall or ceiling. The soles of gecko feet are made up of overlapping adhesive lamellae covered with millions of superfine hairs, or setae, each of which branches out at the end into hundreds of spatula-shaped structures. These flexible pads—each measuring only a few nanometers across—curve to fit inside unseen cracks and divots on the surface. The combined adhesion of these millions of pads holds the gecko in place.