Adamantium

Adamantium is a fictional metal with extraordinary strength and durability. The term is common in science fiction and fantasy, and its properties range from "better than the best alloys known to modern science" to "essentially indestructible".

Examples:

• Adamantium is a virtually indestructible alloy in the Marvel Comics universe.
• Adamantium is one of the strongest materials available to the Imperium of Man in Warhammer 40,000.