While Slipknot's self-titled 1999 debut announced a unique new force in the world of heavy music, the Nine's sophomore offering, Iowa, is where the masked Midwesterners solidified their presence as something singular and bigger than the fleeting popularity of the late Nineties/early aughts nu-metal explosion. And they did so with a little help from Conan O'Brien, on whose show the band had previously made their network TV debut (which you can watch below) in 2000.

A year later, on the August 10th, 2001, episode of Late Night With Conan O'Brien — just weeks before the release of Iowa — all nine Slipknot members took America by storm, headbanging in unison and spitting out "The Heretic Anthem," an aggressive charge on which frontman Corey Taylor claims, "If you're 555, I'm 666!" Historically, 555 is used to signify divinity and wholeness in creation; juxtaposing it with 666, commonly considered as symbolic of Satan, the singer takes on the role of the demonic hero on the song. Live on O'Brien's stage in the clip above, he and his bandmates play out this role with abandon and conviction. Adding fuel to fire is the comedian's introduction with the half-joking disclaimer: "May God help us all."

These days it's hard to imagine a band so closely connected to death metal performing on such a huge platform, but nu-metal — if you can even classify this under that descriptor — was just reaching peak popularity. Enjoy the trip through down memory lane and relive a time when bands this heavy infiltrated the mainstream for a few short years.