Hugh Jackman's Wolverine could return to the MCU, but his future in the franchise has been challenged by Captain America: Brave New World.

There, adamantium is a man-made steel alloy. In the 616 timeline, however, we've just found out its origin is as alien as vibranium's, and Earth's scientists are considering it an all-new element. Red Hulk's appearance in the fourth Captain America movie brings back the quite silly Marvel science of gamma rays to the forefront of the MCU.

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.