To the Muscogee people, the Horned Serpent is a type of underwater serpent covered with iridescent, crystalline scales and a single, large crystal in its forehead. Both the scales and crystals are prized for their powers of divination.
Among Cherokee people, a Horned Serpent is called an uktena. Anthropologist James Mooney, describes the creature:
‘Those who know say the Uktena is a great snake, as large around as a tree trunk, with horns on its head, and a bright blazing crest like a diamond on its forehead, and scales glowing like sparks of fire. It has rings or spots of color along its whole length, and can not be wounded except by shooting in the seventh spot from the head, because under this spot are its heart and its life. The blazing diamond is called Ulun’suti—”Transparent”—and he who can win it may become the greatest wonder worker of the tribe. But it is worth a man’s life to attempt it, for whoever is seen by the Uktena is so dazed by the bright light that he runs toward the snake instead of trying to escape. As if this were not enough, the breath of the Uktena is so pestilential, that no living creature can survive should they inhale the tiniest bit of the foul air expelled by the Uktena. Even to see the Uktena asleep is death, not to the hunter himself, but to his family.’
Source: Horned Serpent – Wikipedia