Adamantium

Fictional alloy. First appears in Marvel's Avengers #66 (July 1969), by writer Roy Thomas and artists Barry Windsor-Smith and Syd Shores. First presented as part of the character Ultron's outer shell,[3] but best known as the substance bonded to the character Wolverine's skeleton and claws.[4][5][6] Adamantium's defining quality is its near-indestructibility. Adamantium is not depicted as a naturally occurring metal but as having been inadvertently invented by fictional American metallurgist Dr. Myron MacLain in trying to recreate his prior discovery, a unique alloy of steel and vibranium. Despite its potential uses in armament and armature, adamantium is rarely used due to high cost and inability to be reshaped. Other forms of adamantium of varying durability are mentioned in the Marvel Universe, including Secondary Adamantium, Adamantium Beta and Carbonadium.[7] Besides Ultron's outer shell and Wolverine's skeleton and claws, Adamantium is associated with a number of other characters and implements including but not limited to, Bullseye's spinal column, certain iterations of Captain America's shield[8] and Lady Deathstrike's skeleton and talons. Adamantium is also used in the Games Workshop universe of Warhammer 40000 and the MMORPG Maplestory.