Duke's avant-garde streak takes over at the edges of his catalog. His pre-funk records are littered with abstract pieces like “Echidna's Surf,” a fusion piece composed by Frank Zappa and suffused with cosmic textures and synthy bass, and “Nigerian Numberuma,” a spaced-out pointillist number that utilizes the percussiveness of African rhythms. Another experimental cut is the swirling “Phase 7,” from his orchestral jazz work, Muir Woods Suite.