Colossus is a mutant with the ability to transform his entire body into a form of "organic steel", with properties similar to osmium but of still unknown composition. Colossus must transform his entire body into this armored state; he cannot transform only a portion of his body. When he transforms, he gains approximately in height; official figures state his height at about in transformed state versus in normal human form. His weight is more than doubled. In his armored form, Colossus possesses superhuman levels of strength, as well as superhuman stamina and durability. His physical strength is currently greater than when he first joined the X-Men due to the realignment of his cells by Magneto following an injury during the Mutant Massacre. While in his armored form, Colossus requires no food, water or even oxygen to sustain himself and is extremely resistant to injury. He is capable of withstanding great impacts, large caliber bullets, falling from tremendous heights, electricity, and certain magical attacks. While he has great resistance to temperature extremes of hot and cold, extreme heat followed by rapid super-cooling has been shown to cause damage. As he is vulnerable to the anti-metal Antarctic Vibranium in his metal form, his body instinctively shifts to human form when faced with an Antarctic Vibranium weapon.