It turns out one of Metallica's most popular guitar riffs owes a little something to Soundgarden. “Soundgarden had just put out Louder Than Love. I was trying to capture their at­titude toward big, heavy riffs,” Metallica guitarist Kirk Hammett told Rolling Stone in 2008.

“It was two o’clock in the morning. I put it on tape and didn’t think about it. When [drummer] Lars [Ulrich] heard the riff, he said, ‘That’s really great. But repeat the first part four times.’ It was that suggestion that made it even more hooky.”

And therein lie the roots of "Enter Sandman.”

There are, of course, other connections between the two bands. They made a memorable appearance together at Lollapalooza in 1996, and both bands were set to play Rock on the Range this spring; Cornell's death came to light on May 18.

At Metallica's May 19 show in Foxborough, Massachusetts, they publicly dealt with the horrific news. Frontman James Hetfield said, “We forgive you, Chris” after the band played “The Unforgiven.” At that same show, bassist Robert Trujillo played a bit of Soundgarden’s “Black Hole Sun.”

Let's get back to that controversial 1996 Lollapalooza appearance for a moment.

“I think that the bill on this year’s Lollapalooza is pretty good,” Hammett told Guitar World at the time. “It may be a little top-heavy because of us and Soundgarden, but it’s certainly stronger than last year’s. F— all those f—ing elitists who say ‘Metallica’s not alternative’ or ‘They’re too big of a band to play Lollapalooza.’ They’re just being very narrow-minded. I’ve been to every single one; I’ve actually jammed at a few too. When Ministry was out, I played with them a few times, and I did the same with Primus. I’ve f—ing loved Soundgarden since 1985 or ’86.”