When Steelhooves was chosen as the Primarch of the 7th legion the decision was questioned by the first 6 primarchs due to his physical state… His body, fused to an archaic suit of armor from the Dark Age of Technology, however using the same surgical magic that would be used to cut Puppysmiles from her hazard suit, Steelhooves was liberated from his armored body and his body was healed by various healing megaspells. The ghoulifcation caused by the Life-Eater virus was never truly cured, even his gene-sons, the space marines of the Imperial Fists, have the pink-stained eyes and distinctive voice of a ghoul, although this gives both him, and his sons greater resistance to powerful radiation, they can survive for long stretches of time before asphyxiation, and they can regenerate at a far greater rate than an average space marine, although unlike the marines of the 14th, they aren't immune to the Life-Eater Virus, nor can they survive without oxygen. Just after the battle aboard the Vengeful Spirit, it was Steelhooves who saved the Empress's Life, and when Stygius the Despoiler launched the first Black Crusade, Steelhooves disappeared, presumably giving his life to save the Imperium.