The hottest and/or saddest speculation in music this week has been centered on a potential Nirvana performance at Thursday’s Rock And Roll Hall Of Fame induction—and namely, on who would front the group in Kurt Cobain’s absence. And if a picture posted to the Foo Fighters Instagram account is any indication, it might be Joan Jett. The photo posted yesterday shows Jett’s Melody Maker guitar alongside Krist Novoselic’s bass, Pat Smear’s guitar, and Dave Grohl’s drums in some sort of recording or rehearsal studio. While a mere photo doesn’t mean definitively that Jett is going to take over for Cobain, it seems like a pretty good sign that some sort of collaboration is in the works. And given the timing, it makes sense to assume it’s Rock Hall-related. At least it’s Joan Jett and not, say, Adam Levine.