Fracta (IBs)

The Fracta were smaller and less powerful versions of the Hōgyoku which were considered to be Prototypes of the mighty stone, the Fracta were designed apparently from a pair of Stones that had been blessed by Kidō capable of altering the very nature of the Soul King's Kingdom which the responsible Kidō may have been cast by the Soul King himself, they have apparently been placed into limit production and put into hosts by former 12th Division Captain Dément Connaissance roughly 1000 years before the Invisible Bane series and they inspired the creation of the two failed Hōgyoku by Sōsuke Aizen and Kisuke Urahara.

Trivia

 * Fracta is a Latin word, one of many, meaning "Shattering". Possibly in regard to "fracturing".