High Quality Content by WIKIPEDIA articles! The XM-X Crossbone Gundam, also known as the F97 Gundam Formula 97, is a series of high-performance mobile suits developed by the Earth Federation`s Strategic Naval Research Institute (SNRI) in the Universal Century timeline of the fictional Gundam metaseries. It appears in Yoshiyuki Tomino`s manga Mobile Suit Crossbone Gundam, as well as its sequels Mobile Suit Crossbone Gundam: Skull Heart and Mobile Suit Crossbone Gundam: Steel Seven.