Precompressed helical spring toy, marketed as a ‘Slinky’. Invented in the early 1940s by American, Richard James. Plastic Slinkies were manufactured in the 1970s, partly because they were not an electrical hazard for young children!
A Slinky moves down a flight of stairs end-over-end and appears to levitate in the process. They have been used by teachers to simulate waves and as mobile radio antennae, as well as in zero gravity experiments in the Space Shuttle.