"An otter," said the legend, "in days long gone by, had with great difficulty lighted a fire on the bank of a river. The sun first came to warm itself by the fire, and while the otter had gone on one of its aquatic expeditions, the moon arrived too. The sun and moon together, feeling in a mischievous mood, put out the fire with water not extra clean. Then they ran for all they were worth. The otter, feeling cold, came out of the water and, to its amazement, found the fire had been extinguished.
"'Who did it?' cried the furious otter, wishing to kill whoever had put the fire out. While its anger was at its highest the otter perceived a toad, which was accused of extinguishing the fire because its legs were as red as fire.
"'Do not kill me!' appealed the toad. 'Put your feet on my belly.' The request was at once granted. The toad opened its mouth wide, and with the pressure of the otter's paws upon its body a burning coal was ejected from its interior anatomy. The otter spared the toad's life in recognition of its services in preserving the fire. That is why the otter and the toad have been friends ever since."
It was not easy to collect legends from the Bororos, as only few of them were inclined to speak. The same legend I found had many variations, according to the more or less imaginative mind of the narrator.
Here is an extraordinary explanation of the origin of lightning.
Bororo Women, showing Method of carrying Children.
Bororos showing Formation of Hands.