An Example of a Necker Cube and an Impossible Cube (One Arm Runs Across the other but is still Straight, which can't happen in 3D; it's an Optical Illusion).

Tags: Clip Art, Clipart, Cube, Geometry, Image, Impossible, Impossible Cube, Inkscape, Mathematics, Media, Necker Cube, Optical Illusion, Outline, PNG, Public Domain, Shape, SVG, Wireframe