Adamantium

Appearing as a child, this means this is a Wolverine long before the metal resource known as Adamantium was forcefully attached to his skeleton, so his claws are simply comprised of bone.

Central to the origins of the former is adamantium, a metal which, according to rumors, is only now being discovered during the events of the fourth film.

However, Sabretooth had the adamantium skeleton and claws, and Wolverine didn't.

It was previously reported that the Celestial Tiamut would be transformed into an island that would be the home of Adamantium in the pic.

Wolverine's adamantium bones are infamously durable.

Wolverines' adamantium claws can cut the Hulk, so they can cut Abomination, too.

Adamantium technically makes its Marvel Cinematic Universe franchise debut in Deadpool & Wolverine (which is now playing in theaters everywhere), but the vast majority of that movie doesn't technically take place in the MCU canon, also known as Earth-616.

Claremont foresaw a battle between Wolverine and Colossus where the latter tears out Wolverine's claws, causing the adamantium to slowly be purged from his body altogether.

Even with his unbreakable adamantium skeleton, a horse kick can't be a fun experience.

This time, Ultron is defeated when Hawkeye knocks him into a vat of molten adamantium, which hardens around Ultron and freezes him in place.

Adamantium hasn't been utilized in the entire MCU thus far, and adding Wolverine into the mix could presumably introduce that iconic material.

A foot-long apiece and coated in nigh unbreakable adamantium, they can cut through nearly anything and have allowed Wolverine to defeat all manner of opponents over the years including ones that he should have lost to.

Cable singlehandedly dispatched all of the X-Men, with Wolverine attacking him in a berserker rage, forcing Cable to reveal his own adamantium claws and revelation that he was a future incarnation of Wolverine.

Even having his adamantium skeleton ripped out couldn't keep the ol'Canucklehead down.

In the aforementioned Wolverine's adamantium skeleton was forcibly removed by Magneto in battle.

Jimmy and Kitty learned that he had inherited Wolverine's powers, along with the ability to form an adamantium coating around his claws.

Like other individuals with adamantium inside of them, Creed suffers from a slow and gradual poisoning from the rare metal battling against his healing factor.

One of the biggest mysteries of early Wolverine stories was where his adamantium skeleton came from and why he couldn't remember anything about his past.

The "Fatal Attractions" event, for example, saw Magneto rip the Adamantium skeleton out of Wolverine's body - and although Logan came within a hair's breadth of dying, he managed to heal.

The problem Aang has against Ultron is the android's adamantium shell.