Colossus is a mutant with the superhuman ability to convert the tissue of his entire body into an organic steel-like substance, granting him superhuman strength and a high degree of resistance to bodily harm. This substance, resembling organic steel, is of unknown composition but appears to be analogous to osmium and to carbon steel. He is able to transform into this armor-like state at will (the process is virtually instantaneous) and remain in that form for an as yet undetermined amount of time. (The longest time he has remained in armored form so far has been five days). Once in his armored form he remains so until he consciously wills himself back to normal. If he is rendered unconscious, however, he spontaneously reverts to his normal form. While in his armored state, Colossus possesses the same degree of mobility that he does in his normal form.
The process by which Colossus transforms himself to armored form and back (including his gain of additional mass from an unknown, perhaps extra-dimensional, force) remains unknown. Colossus cannot become partially or selectively armored; his body is either entirely converted or not. Even his eyes become steel-like; his eyeballs can withstand and deflect the impact of a .45 caliber bullet.
