Nothing gets the Internet abuzz quite like an illusion, whether it's "Laurel or Yanny", the skinny legs selfie, or the one that started it all, that dress. The latest to make the rounds and provide a nugget of escapist entertainment in a world that is literally on fire involves a very oddly shaped mug.
This particular illusion, unleashed upon the world by a man called Tony Fisher, will have you and your friends debating whether it's round or square.
In the video Fisher posted on YouTube, the mug is placed on a table in front of a slanted mirror. In the foreground, the rim appears to be circular. In the mirror, it is most definitely square. Next, Fisher picks up the mug and spins it around, causing it to shapeshift in what can be described as a confusing medley of circles, squares, and rectangles.
Then, Fisher pours milk into it because it "shows up better than other liquids in the gold mug" and begins to stir with a metal teaspoon. "The milk and spoon were used to show there was no video trickery," he explained in the video description.
So, what exactly is going on? Tony Fisher is a British-based puzzle designer, who is also responsible for creating a record-breakingly large Rubik's Cube in 2016. To make this mind-bending mug, he exploited a shape first used by Japanese engineer and artist, Kokichi Sugihara, in his "ambiguous cylinder illusion".
While the mug looks angular from certain perspectives, it is not a true square. Instead, it's a funny old mash-up of a square and circle (a squircle?). To produce the illusion, two of the sides arch upwards and two dip downwards. This "corrects" or "blends" the hybrid shape into a square or a circle depending on the angle – as YouTube user Make Anything explains in the video below.