According to the book The Voyage of the Dawn Treader by C. S. Lewis, the Duffers, along with a magician, Coriakin, inhabited a small island near the edge of the world of Narnia in the middle of the ocean. They were discovered by the explorers on the Dawn Treader after they landed on the island to rest. The travelers gave the Duffers oars and instructed them to jump on the water as lightly as possible and row themselves about on their single, large foot. Before leaving, the name Monopods is given to them, however, the unintelligent Duffers soon mixed up the name, saying " 'Moneypuds, Pomonods, Poddymons.' " Eventually, they settled with the name Dufflepuds.
In their monopod form, their one leg is usually three feet long, and ends in a large canoe-like foot. When they sleep, each lies on his back with his foot acting as a kind of umbrella over them. According to Brian Sibley's book The Land of Narnia, Lewis may have based their appearance on drawings from the Hereford Mappa Mundi.