Easily the most popular X-Man, Wolverine's most recognizable trait is his set of adamantium claws. Unbreakable and utterly dangerous, the metal weapons are a reflection of Wolverine's own personality. For the longest time, however, the true nature of these claws was unknown, and they were believed to be unrelated to Wolverine's mutant powers.
A fateful encounter with a once again villainous Magneto finally revealed the truth about these claws, albeit at the expense of their stainless metal finish. With Magneto having removed the adamantium from his skeleton, Wolverine would become wilder than ever. Transforming into a vile animalistic caricature of what he once was, Wolverine's heroic heart would test its mettle after his bones were stripped of theirs.
Fatal Attractions
The removal of Wolverine's adamantium and the revelation of his bone claws all transpired in the 1993 crossover event "Fatal Attractions." Written by Fabian Nicieza and Scott Lobdell and drawn by a number of artists such as Adam and Andy Kubert, the storyline saw Magneto, who had by then been an ally of the X-Men for years, return to maniacal villainy. Rather fittingly, this return to the old status quo also marked the 30th anniversary of the X-Men franchise as a whole.
The story has Magneto, who at the time was believed dead, offering mutant sanctuary on his ship, the Avalon. Reeling from the continued tragedy of the Legacy Virus on the mutant population, Magneto planned to wipe out humanity from the Avalon. The X-Men stood in his way, but in the process lose Colossus to Magneto's side, as the Russian had become disillusioned with Xavier's talk of peace. The United Nations attempts to use protocols to keep Magneto from using his powers upon the Earth, but he retaliates by decimating the world's electrical systems.
Xavier, wearing a Shi'ar exoskeleton, is forced to take the fight to Magneto on Avalon. Magneto keeps his opponents at bay, including his son Quicksilver, but Wolverine manages to get the drop on him. Wolverine tries to stop the Master of Magnetism once and for all, almost lethally slicing his torso. Enraged and clearly uninterested in their old song and dance, Magneto does even worse by Wolverine, liquefying the adamantium on his skeleton and ripping it out of his body. This overloads even Wolverine's incredible healing factor, leaving the mutant near death. It's only in the succeeding issue, where Wolverine pops his claws again in pain, that it's shown that they were always in fact bone claws which adamantium had been bonded to.
Feral Wolverine
Wolverine would decide to end his ongoing feud with Sabretooth by permanently ending Sabretooth himself. The X-Men are strangely shocked at Wolverine's violent behavior, but Xavier's discovers that it's part of a natural regression. Apparently, Wolverine's true mutation was a bestial, primitive existence, and the experimentation that was done to him by bonding him with adamantium somehow halted this process. Wolverine's regression would continue over the next few issues before Stryfe kidnapped him. The evil alternate Cable planned to rebond his skeleton with adamantium, turning him into a loyal servant of Apocalypse in the process. The adamantium doesn't take, but the experimentation pushes Wolverine over the edge into mindlessness. Now truly devolved, this Feral Wolverine had an incredibly animalistic appearance, with bulging muscles, wilder hair, and no nose.
Eventually, Elektra would somehow be able to draw a sense of humanity out of Logan's psyche, but he still maintained his savage appearance. This would be the status quo for a little while, with Wolverine even rocking a bandana in the place of his old cowl. New artists would begin drawing him with a human appearance, which initially was explained as involving an image inducer for a holographic disguise in public. However, this explanation was dropped and Wolverine's savage nature was ever brought up again. Apocalypse did eventually succeed in both reuniting adamantium to Wolverine's skeleton and brainwashing, but he was able to shake off the latter. Much like his "hot claws," however, Wolverine's feral state was quickly forgotten.