Ancient Alien Computer

An ancient piece of corroded metal is more than it seems: an alien-looking device of intricate dials and cogs; there are over 30 gears inside and some gears have up to 65 teeth on them. Using cutting-edge imaging technology, experts examine what could actually be a 2,000-year-old computer.
How can an ancient Roman cup change colour? It's not an optical illusion. It really does change colour from red to green.