Klein bottle

Klein bottle is one of the strangest surfaces. It has only one side and don't have any boundaries. It was first described in 1882 by German mathematic Felix Klein. The initial name given was "Klein Fla-e-che" (Fläche = Surface). However, this was wrongfully interpreted as Fla-s-che, which ultimately, due to the dominance of the English language in science, led to the adoption of this term in the German language, too.
This object can exist without selfintersections in four dimensional space.