Mbói Tu'i has the form of an enormous serpent with a huge parrot head and a huge beak. He also has a red, forked tongue the color of blood. His skin is scaly and streaked. Feathers cover his head. He has a harmful look that frightens everyone who has the bad luck to be found with him. He patrols the swamps and protects amphibian life. He enjoys the humidity and flowers. He lets out an incredible powerful and terrible squawk which can be heard from very far off and which instills terror in all who hear it. He is considered the protector of aquatic animals and the wetlands.