From wikipedia: When Os Mutantes was formed, it combined influences from psychedelic acts from the English-speaking world like The Beatles, Jimi Hendrix, and Sly & the Family Stone with bossa nova, tropicália, samba and the cultural legacy of the Brazilian art vanguards from the modernist movement.
Os Mutantes is one of the most well-known and influential rock bands in Brazil. In addition, many contemporary underground or independent bands in the United States and Europe cite Os Mutantes as a major influence. Kurt Cobain publicly requested a reunion tour from the trio in 1993, writing a letter to Arnaldo Baptista. Cobain was introduced to them by Pat Fear from White Flag (whose collaboration with Redd Kross and other friends under the name The Tater Totz was the first American band to cover or even cite Os Mutantes on their 1988 LP Alien Sleestaks from Brazil).