This circular artefact was left on the Moon by distant visitors and discovered by the Gudgenauts on their recent Moon walk. ANU researchers believe that it is a Data Puk, designed for use with a Puk reader. It reveals detailed instructions guiding the layout and construction of a luna metropolis capable of sustaining millions. It may be that humankind is not the first to set foot on the Moon and that the urban grid holds truly universal appeal. Who would have thought!