Fleetwood Mac is widely recognised as a pop and rock band fronted by Lindsey Buckingham and Stevie Nicks, yet the group's origins under founder Peter Green were markedly different, rooted in blues influences that produced a heavier, more complex sound before the band pivoted toward commercially accessible melodies during the mid-1970s.

Metallica guitarist Kirk Hammett has credited Peter Green's "The Green Manalishi (With The Two Prong Crown)" as a key influence on heavy metal's development, praising the track's inherent darkness and atmospheric depth despite its creation in an era predating modern high-gain amplification and advanced guitar technology. Hammett noted that the song's mystifying qualities and psychological weight reach into territory that metal would later explore and amplify, demonstrating that sonic heaviness derives from compositional intent rather than technological power alone.