Transparent coffee cup Photo by: jkvandersteen What am I looking at? This transparent coffee cup is a perfect physical illusion. The reflection of the saucer in the smooth surface of the cup completes the floral pattern nicely. More optical illusions:Ominous birdSmile!Bent over the deskBig cat on the roofSelf-assemblyBride WaterfallFootprint in the sandNext to the boat