A long-lost Mick Jagger-Carly Simon collaboration, believed to be titled "Fragile," from 1972 has been unearthed by a Rolling Stones collector. The Associated Press reported London entrepreneur Matt Lee "declined to say where the tape of the song came from. But he said he sent a digital copy of the song to Rolling Stone magazine because they promised to give it to Simon." Lee explained, "I’m not doing it for the money. I’m a collector. My motive for sending it to Rolling Stone was to pass it to Carly."

Back in 2016, Carly Simon spoke to Rolling Stone about the team-up stating, "We had this little back and forth at the piano for about an hour, (singing) 'Funny, funny, funny, funny, funny, How love can make you cry.''" On the demo recording, after the song finishes, a voice -- believed to be Simon's -- says, "good song." Fans have possibly already heard a bit of the tune in the Stones infamous and long-unreleased 1972 tour film C***Suckers Blues, where Jagger can be heard singing an unknown tune, with the lyrics: "It’s funny, funny, funny."

Back in 2011 Carly Simon revealed that Mick Jagger took a 1974 collaboration by the two and co-credited Keith Richards instead of her. At the same time that Jagger laid down backing vocals on Simon's 1972 track and eventual chart-topper, "You're So Vain," she says that she and Jagger went on to co-write a future Stones classic -- which found her edged her out of the songwriting credit.

Simon was quoted on Marc Spitz' recent biography, Jagger: Rebel, Rock Star, Rambler, Rouge, as saying, "We wrote a song together that became a song on the next (Rolling) Stones album (It's Only Rock N' Roll) called, 'Till The Next Goodbye.' I thought that was going to be a joint venture, but I'd never heard from Mick about how he'd like me to share the royalties."

Carly Simon recalled recording the backing vocals to her one and only chart-topper, "You're So Vain," with Mick Jagger and Harry Nilsson during the '72 sessions for her No Secrets album: "Y'know, Harry and I were in there, we were doing it, it didn't quite have the right character, because it wasn't tough. I didn't ask Mick to come over because I needed a tough voice. Mick just showed up, and so we invited him to join us. And so the three of us were singing it together. And it sounded too sweet. The three-part harmony didn't work, but Harry was the first to notice it, and Harry said, 'Well, why don't the two of you try it together?' Y'know that's how it happened -- but more than anything Harry wanted to go out and have a drink (laughs)."

AUDIO: CARLY SIMON ON RECORDING 'YOU'RE SO VAIN' WITH HARRY NILSSON AND MICK JAGGER