It's a fascinating time capsule of where Cobain was at sonically, because it's so different from the band's album which would follow. On the mixtape, unearthed by Dangerous Minds, Cobain tinkers with noise rock, layering samples from the radio and his home collection of recordings along with sounds and drones. By the time he made it, noise rock - an offshoot of Krautrock - was in full swing in San Francisco, New York and Washington, D.C., especially.

Cobain's take on it spans 15-plus minutes and includes moments from Jimi Hendrix's speech at the Monterey Pop Festival, Fred Flintstone screaming after his bowling ball, the Jackson Five's "ABC," James Brown's "Hot Pants" and, most surprisingly, William Shatner's cover of "Wild Thing."

Cobain would have painstakingly compiled each sample from its source manually, well before YouTube or Spotify existed, using a four-track cassette recorder.