Circles are compressed to rectangles. These are then pressed to form squares, which then are minced into a sausage.
NOTE: You'll need the image <a href="//commons.wikimedia.org/wiki/File:Moving_illusion_catalyst.png" title="File:Moving illusion catalyst.png">Moving illusion catalyst.png</a> for this to work properly
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<span class="int-own-work" lang="en">Own work</span>