In the Showa era films, Gamera was a gigantic, prehistoric species of tortoise, reawakened by an accidental atomic blast in the Arctic during a dogfight between US and Russian fighters. The film mentioned that Gamera had appeared before, from pictographs depicting Gamera, and warning of his ability of flight. Gamera's origin was given that he was a leftover from eons in the past. Gamera was already capable of flight and breathed true flames, rather than radioactive energy when he was reawakened. And while it was known that he fed on flames, the explanation for this power is that the age in which he lived lacked oxygen but was volcanically active thus causing Gamera to feed on fire.