Ambiguous Tubes optical illusion
Professor Kokichi Sugihara of Japan has developed a number of illusions such as this one. The two tubes are joined together. When viewed from one direction you see a square yellow tube and a circular blue one. When you turn the tubes around by 180 degrees, the yellow tube now appears circular and the blue one appears hexagonal. The effect is even more startling if you place a mirror behind the tubes, so you can see both views at once. The item came into the collection as part of the Grand Illusions (www.grand-illusions.com) Christmas Pack 2018/2019.