B-sides
Part one of the single contains the b-side song "Cuttooth", with piano and bass working collectively and fluently, and a few samples running in and out throughout the song. The track is 5 minutes and 24 seconds long, though early versions were described as being much longer. "Cuttooth" is notable for having been mentioned 12 times in Ed O'Brien's online diary of the studio process for recording Kid A and Amnesiac, leading fans to expect it as a centrepiece of the band's new material, though the song would not make the cut on either record. Ed stated they wanted this track to sound like German Krautrock group Neu!. Some of the lyrics of "Cuttooth" ("I don't know why I feel so tongue tied / I don't know why I feel so skinned alive") were later used in the Radiohead song "Myxomatosis," appearing on the band's 2003 album Hail to the Thief. "Cuttooth," like its fellow b-sides "Talk Show Host" and "The Amazing Sounds of Orgy", has since gained unexpected popularity among the fandom.
The "full length" version of "Life in a Glasshouse" found on the single is derived from the same performance as the version found on Amnesiac, but differs in that it lacks the opening electronic effect, and features slightly more soloing by jazz trumpeter Humphrey Lyttelton and other members of his band before Yorke begins singing.
Part two of the single contains the original studio-recorded version of "Fog," an ambient and melodic song, mainly bass-driven, and featuring some creative use of tambourine. This version of the song is 4 minutes 5 seconds long and differs from Thom Yorke's solo piano version sometimes played live. That brief live piano version was itself released as a b-side two years later, during the band's Hail to the Thief era, at which point it was nicknamed "Fog (again)." The song had also been known as "Alligators in New York Sewers" since its live debut in Israel in 2000. Only the solo piano version has ever been played live, and Yorke professes to be dissatisfied with the recording found on the "Knives Out" single. Also in the second part of the single's release is "Worrywort", a slow and dreamy electronic song again featuring unique percussion effects or beat-boxing, which is 4 minutes 37 seconds long.
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