If you can, take a phone flashlight and shine it in. Another tip is if you have one of those ear things that light up and you can look into people's ears. Try shaking it around just slightly to see if you can hear it in there, if not it has fallen elsewhere.
Simultaneous contrast refers to the way in which two different colors affect each other. The theory is that one color can change how we perceive the tone and hue of another when the two are placed side by side.
