Seeming figures visual illusions

Lecture

Kanish Triangle.
There is no equilateral triangle. He just seems.
Big and small diamonds, too, only seem.
See also McColloff effect.
Do you see the Necker cube here?
But there is no cube! This is an illusion.
Do you see black circles at the intersection of white lines?
But the figure does not have a single circle.

Square, which is not.
This set of points is perceived as continuously changing patterns of rows and squares.
The effect of striving for a closed loop

The figure in the upper figure is perceived as a cube, and in the lower only as a set of individual pieces.
Where do the arrows point?
Outward or inward shape?
What is it?
Latin "I" or six laps?