The band's debut album, Os Mutantes, is far and away their best -- a wildly inventive trip that assimilates orchestral pop, whimsical psychedelia, musique concrète, found-sound environments -- and that's just the first song! Elsewhere there are nods to Carnaval, albeit with distinct hippie sensibilities, incorporating fuzztone guitars and go-go basslines. Two tracks, ""O Relogio"" and ""Le Premier Bonheur du Jour,"" work through pastoral French pop, sounding closer to the Swingle Singers than Gilberto Gil. Os Mutantes' first album is an astonishing listen. It's far more experimental than any of the albums produced by the era's first-rate psychedelic bands of Britain or America.