Above is a depiction of the Mayan sky god Quetzalcoatl,the feathered serpent.
In pre-Columbian Central America Quetzalcoatl was sometimes depicted as biting its own tail. The Ouroboros, “tail-devouring snake”is an ancient symbol depicting a serpent or dragon swallowing its own tail and forming a circle. Ouroboros symbolism is seen reoccurring across many cultures, in different forms, from Europe to the Amazon.

The Ouroboros often represents self-reflexivity or cyclicality, especially in the sense of something constantly re-creating itself, the eternal return. Jeremy Narby makes the parallel comparison here with the replicating nature of DNA.

Carl Jung interpreted the Ouroboros as having an archetypical significance to the human psyche.

In Gnosticism, this serpent symbolized eternity and the soul of the world.

In Norse mythology, the ouroboros appears as the serpent Jörmungandr, one of the three children of Loki and Angrboda, who grew so large that it could encircle the world and grasp its tail in its teeth.

The organic chemist August Kekulé claimed that a ring in the shape of Ouroboros that he saw in a dream inspired him in his discovery of the structure of benzene.He said that he had discovered the ring shape of the benzene molecule after having a day-dream of a snake seizing its own tail. This vision, he said, came to him after years of studying the nature of carbon-carbon bonds.