In Captain America: Brave New World, Adamantium is discovered in the Celestial Island, and is a key part of the worldwide treaty that Harrison Ford's Thaddeus Ross is championing. In a speech at The White House he says that the metal has numerous health properties and could be the most important discovery since Vibranium.

Before 2023, it would have been unthinkable for a Marvel Studios film to flop at the box office. Regardless, The Marvels failed to, well, marvel audiences, earning a bleak $206.1 million worldwide, while Ant-Man and the Wasp: Quantumania disappointed the studio with only $476.

That's because Captain America: Brave New World brings adamantium into the fold. The substance shows up in the body of the Celestial that emerged from the Indian Ocean in Eternals. Now, it's the cause of international conflict, as major world powers try to control the world's only known adamantium supply.