Boi-tatá [boj.ta.'ta] is a monster from Brazilian folklore. Regionally it is called Boitatá, Baitatá, Batatá, Bitatá, Batatão, Biatatá, M'boiguaçu, Mboitatá and Mbaê-Tata. The name comes from the Old Tupi language and means "fiery serpent" (mboî tatá).
origin
According to legend, Boi-tatá was a big serpent which survived a great deluge. To save itself, it entered a cave and rested in the darkness for centuries, so that its eyes grew. After it left the cave, it went through the fields looking for the bodies of animals to eat, but also sometimes attacked people and animals. It's not like a dragon but most like "Anaconda" the giant snake, that in native language is called "boa" or "mboi" or "mboa". It happens when some biological gas expands from the ground and burns in contact with the air. Mboitata is the same phenomenon as the Will o' the wisp.