First, there are already animals in the world that once breathed fire. In addition to human circus performances, there is also a domestic cow in the Netherlands. Because of flatulence, the owner called a veterinarian. The veterinarian wanted to use a lighter to observe the tongue coating of the cow at night, but the gas exhaled by the cow was actually ignited. Fever burnt. It turns out that the grass eaten by cows is decomposed by microorganisms in the stomach, producing methane gas, which is as flammable as hydrogen. But this fire-breathing is...