This is another version of the earlier spiral, this time using pleasing colours to the eye. Is it a real spiral? The perspective is very convincing in this image, with the central focal point being a pale colour.
Now try following the outermost line you can see, all the way in to the centre. You will not be able to do it, because each circle is separate. The sense of perspective in this illusion really does trick us; we follow the black, red and pale diamonds as they retreat into the distance, and believe that the lines do the same.
It's a spiral, right?
No, these are a bunch of independent circles.
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