Impossible shapes (no ontology)
From Hi.gher. Space
Impossible shapes are shapes which can be identified uniquely in a projection, but appear to be shapes with paradoxical properties.
Impossible triangle
The impossible triangle is the projection of a 3D object with three 90 degree corners. Each corner is in a perpendicular cardinal plane and the entire object is joined up to have a genus of 1. In the projection, the shape appears as a triangle, but the shape cannot possibly exist.
