While it does not look like much, the wire frame drawing of a cube below is actually an ambiguous optical illusion.  The cube can be seen in one of two ways.  Either the lower left face or the upper right face can be seen as the front most surface of the cube.  Can you flip-flop between the two interpretations?

This illusion is named the Necker Cube as it was discovered by Louis Albert Necker in 1832.

Other Optical Illusions You Might Enjoy

Sand Cube

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Hilbert Cube Stereogram by Gene Levine

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Three Fold Cubes

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Magic Floating Cube

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Hollow Necker Cube by Robin Hunnam

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Ambiguous Cubes

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