Theo Jansen creates purely mechanical walking robots that require no electronics and are "fed" by wind sails. They are built to actually respond to the changing environment.
The individual ant is a very simple creature that has about twelve individual thought processes in its decision making. But it is the way that individual ants interact with one another that helps the colony solve complex problems and makes them one of the most successful species on the planet. It is interesting to me that an inventor can come up with a purely mechanical machine that is capable feeding itself, storing energy and making decisions based on changing conditions. I know I am only making a vague and scientifically uninformed comparison here, but the increasing blurring of the lines between what is "machine" and what is "biology" is interesting to me.