Stuff is a shape-shifting artificial organic entity. On behalf of the Shi'ar Imperial Guard, he infiltrated Xavier's School for Gifted Youngsters as "Kato". When the Superguardians (influenced by Cassandra Nova) assaulted the school, Stuff revealed his true form.^[1]

Charles Xavier and Jean Grey eventually eliminated Cassandra Nova as a threat by reducing her mind to an infantile state and placing it inside Stuff. Nova would then be tutored from the beginning of her new life to produce a less-genocidal personality.^[2]

• Shapeshifting: An alien bio-computer able to transform his synthetic form into virtually any conceivable shape.^[3]