Two true circles drawn over the rings, with the same center.
Straight, bent or tilted?
Circles that look square
Are these two rings circles?
Yes: two perfect circles with the same center, though they look like rounded squares.
Why? Each blob is shaded so that its edge seems to lean a little, like a twisted cord. The lean turns round eight times around each ring, and the two rings lean opposite ways, so your brain bends each circle toward a square. Akiyoshi Kitaoka drew the first; this is our drawing.
Picture: Drawn by Science Playground, after Akiyoshi Kitaoka · Wikipedia(opens in a new tab)