Adamantium finally makes its MCU debut in Captain America: Brave New World, which reveals the metal to be the composition of the frozen Celestial Tiamut, whom Sersi petrified in the Indian Ocean ...

Captain America: Brave New World revealed Tiamut is the cause of Adamantium being in the MCU. Kumail Nanjiani has spoken about the trauma he endured from the bad reviews of Eternals.

The events of Eternals was finally referenced in Captain America: Brave New World, revealing that Tiamut's partially formed body was what brought Adamantium to the MCU. As most comic fans know ...