UNIQUE: Hand-signed 'Eigen Druk' in pencil Catalogue raisonné: Bool #441 © The M.C. Escher Company B.V. Although Escher had worked with ribbons and spirals before as source material, he was introduced to the concept of Mobius Strip in 1960. While working on this image, he modeled the ants in 3-D clay in order to get movement correct in the print. He also created paper models of the Mobius structure to further ensure accuracy. The ants marching around their looping DNA-like framework in an endless cycle can be seen as a representation of infinity or perpetuity.