EDIT: Improved AA and outline quality.
Developed by particularly bored scientists, this small snail powers its metallic shell by moving. The energy signals are drawn through the red and green wires and into the shell, and crank the cog. As the cog cranks, it transmits the signals produced by the snail's senses through the yellow and blue wires and out its radio antenna. It has been used as a slow, but inconspicuous spy across Europe.
This isn't going to win any place in the contest, but it seemed fun and I was bored.