Ozma

Ozma is an optional superboss in Final Fantasy IX. A very unusual-looking monster, Ozma appears as a sphere patterned with bright, swirling colors (the top half representing light and good, the bottom half darkness and evil, or, supposedly, Gaia and Terra). Because Ozma is found inside a so-called "Eidolon cave", it can be speculated that Ozma, much like Leviathan, was an Eidolon whose power the summoners couldn't harness, and it was thus locked away. Over the many years since, the legends that gave birth to Ozma would have long since vanished, and the people who used to tell them would be extinct, with the result that Ozma loses whatever form it may once have had and only appears to the party as a swirling mass of energy.