Florence + the Machine are still touring behind last year's 'Ceremonials' album, and last night, singer Florence Welch and her backing band stopped by 'Late Night With Jimmy Fallon' with an orchestra in tow to play that disc's 'Spectrum (Say My Name),' which you can watch above. As stunning as that performance was, it was perhaps even better when Welch sat in with Fallon to duet on a reprisal of 'Balls In Your Mouth,' the BP protest song that the talk show host previously performed with Pearl Jam's Eddie Vedder.

Watch Florence Welch and Jimmy Fallon Sing 'Balls In Your Mouth'