the.com/slinky
a coiled physics demo that walks downstairs purely on its own enthusiasm and gravity.
war babyInvented in 1943 from a spring that fell off a desk
naval originEngineer was designing springs to steady ship equipment
slow signalTop falls before the bottom learns it's dropping
sold countOver 300 million have walked off shelves
space cadetAstronauts tested one in zero gravity; it flopped