Central to the Fon account of creation is the great serpent Aido-Hwedo, who carried Mawu-Lisa in its mouth as the work of creation proceeded, and whose movement across the still-forming earth is said to have shaped its winding rivers and coastlines. Once creation was complete, Aido-Hwedo coiled itself beneath the earth, its countless coils supporting the weight of the world both above and below the surrounding sea, an ongoing labor rather than a finished task.
Because the serpent must periodically shift position to remain comfortable under so great a burden, its movements are held responsible for earthquakes, felt whenever Aido-Hwedo stirs beneath the ground. Herskovits' account of Fon cosmology records a further, eschatological dimension to the serpent's role: the world's mountains, its human population, and the accumulated weight of ordinary life are believed to grow heavier over time, and Aido-Hwedo is destined eventually to grow exhausted under a burden it can no longer bear, at which point it will release its coils and the earth will collapse and sink beneath the sea, an end this entry of Fon cosmology anticipates without specifying exactly when it will occur.
Aido-Hwedo is generally depicted as ouroboric, its body forming a continuous circuit, and its association with rainbows, mountain ranges, and winding rivers reflects the same serpentine, coiling logic across several different registers of the visible landscape at once, so that geological features that might otherwise seem unrelated are read within Fon cosmology as different traces of the same single, continuously active being.