Tireflies, active components
Active components of the tireflies. The circular structure is a coil spring, which we are seeing end-on. When the structure is bumped, the spring bends until it hits one of the walls around it. When that happens, the circuit turns on and blinks for a little while. A neat trick is to instead force it to blink all day long by making the spring touch the walls all the time.
Read more about this project here.