The Fon creation account gives the creator a servant, and the servant is the most vivid thing in it. Aido-Hwedo is the rainbow serpent, who carried Mawu in his mouth while the world was being made, and whose winding movement across the ground is why rivers and hills follow the courses they do. Where the pair rested, mountains stand, made of the serpent's dung.
When the making was finished the world was too heavy. Aido-Hwedo was set beneath it, coiled in a circle with his tail in his mouth, in the sea, to hold it up. Because he cannot bear heat, the ocean was made cold for him. He is fed by red monkeys who forge iron bars for him under the sea, and when the bars run short he shifts from hunger, and the shifting is felt as an earthquake. When the bars run out entirely, he will eat his own tail, and the world will slide into the sea.
This is not decoration. It is a working cosmology with a mechanism, a dependency and an ending, and it puts the continuation of the world on a serpent's appetite. Dan, the serpent, is served in his own right as a vodun of movement, wealth and continuity, and his shrines carry iron and the colours of the rainbow.
The serpent crossed the Atlantic with the rest. In Haiti, Damballa is a serpent lwa of the Rada rite, whose name and whose associations with water, wealth and continuity come from the same source, and whose arrival in a service is recognised by the serpentine movement of the person he mounts.