Question for Geeks

Velcro was discovered by Georges de Mestral, a Swiss engineer who, in 1941 went for a walk in the woods and wondered if the burrs that clung to his trousers (and to his dog) could be turned into something useful.

How many other things can you think of, that the design in nature has inspired?

Photograph: The hooks of a piece of Velcro.
Source http://www.flickr.com/photos/olivepixel/220573311/