Nitinol is a special alloy of nickel and titanium that has an interesting property called shape memory. This means the metal can undergo deformation at one temperature, then recover its original shape at another.
This sample’s transition temperature is around 40°C (104°F) which can be achieved using hot water or a hair dryer. It’s trained shape is straight and unbent. So if you put it in a bowl of very hot water it will instantly straighten out.
Once cooled, you can then bend it to any shape and repeat the process. It can even be retrained to remember a new shape at much higher temperatures. Nitinol has great potential for use in systems where latent heat energy can be utilized to trigger a task. Nitinol motors are already being developed.
NASA has even experimented with using this material for wheels on future rovers.
Wire is approximately 7"