On Wednesday, the US Department of Tresury and Federal Reserve unveiled the design for a new $100 bill that includes several anti-counterfeiting security measures. The bill, which replaces one designed in 1996, will begin circulating in February, 2011.
A 3D security ribbon on the front of the bill contains images of bells and 100s that move and change as the currency is tilted. The bell in the inkwell changes color from copper to green, which makes it seem to appear and disappear.