Marvel: Organic Steel Form

Piotr Rasputin (Colossus)
Colossus is a mutant with the superhuman ability to convert the tissue of his entire body into an organic steel-like substance. This substance, resembling 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. Once in his armored form, he remains so until he consciously wills himself back to normal. If he is rendered unconscious, however, he spontaneously reverse to his normal form.

While in the armored state, Colossus possesses the same degree of mobility that he does in his normal form. The conversion from flesh and bone to organic steel is accomplished by a psionic whole-brain interface with an ionic form of osmium, an extremely dense metal, located in another dimension. In willing the act of transformation, Colossus actually exchanges osmium atoms for his carbon atoms. The psionic interface with the other dimension re-creates all of Colossus's body in functionally similar organic ionic-osmium materials. The process by which Colossus gains 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.
 * Superhuman Strength: After transforming into his armored state, Colossus possesses vast superhuman strength. As a teenager, he was sufficiently strong enough to be listed as a class 70. However, as a fully mature adult, his strength has increased to the point that he is listed at exactly class 100.
 * Superhuman Stamina: Also, while in armored form, Colossus' musculature produces considerably less fatigue toxins than the musculature of a normal human. At his peak. he can physically exert himself at peak capacity for several days before the build-up of fatigue toxins in his blood begins to impair him.
 * Superhuman Durability: In his armored form, Colossus is invulnerable to most forms of physical harm. His armor is capable of withstanding ballistic penetration, including that of a 155 millimeter Howitzer shell. He can survive extremes of temperature from 70 degrees above absolute zero to approximately 9000 degrees Fahrenheit. He can survive a collision with a load, ten ton flatbed truck at 100 miles per hour or an explosion of 4500 pounds of TNT. He can also survive falls from great heights while in his armored body.