A surface with only one side and one boundary, as produced by taking a strip of paper, twisting one of the ends by 180°, and then attaching the two ends. It was developed by the German mathematicians August Ferdinand Möbius (1790–1868) and Johann Benedict Listing (1808–82) in 1858. The German-Swiss chemist Edgar Heilbronner suggested in 1964 that it is possible for molecules with the topology of a Möbius strip to exist. Such molecules have since been synthesized. See also Heilbronner’s rule.