A Google Map of Mexico City's Street Vendors

Scientists will sometimes stain a certain element of organic matter to enhance its visibility under a microscope. These surreal and sharply colored images could be mistaken for such contrast-enhanced biological material.

They are actually Google Earth photos of tianguis, the famous street markets that spring up all across the Distrito Federal. In a collection compiled by Fabian Neuhaus of UrbanTick, and featured on Nicola Twiley's Edible Geography on Monday, the markets -- sheltered beneath red plastic tarps, which gives them their distinctive appearance from the air - look more like living organisms than groups of merchants. They sprawl down certain streets, seemingly chosen at random from an endless grid, turning corners or branching off into side streets. Their logic, from above, is mysterious and undeniable.