Originally known as 'Arpeggi', the name comes from the chorus 'I get eaten by the worms/And weird fishes' and the plural of the Italian word 'Arpeggio'.

It was first performed by guitarist Jonny Greenwood and lead singer Thom Yorke in 2005 as an atmospheric string-based piece, backed by the Nazareth Orchestra.

In 2006, the song was brought into a rock music setting, and a full-band version was premiered which included a driving rock beat.

On October 1, 2007 the band announced that the song would appear on In Rainbows as the fourth track. The version that appears on the album is similar to the 2006 version with Phil Selway's driving drum beat, although it retains many of the atmospheric, bubbly qualities of the 2005 version.

This song was #17 on Rolling Stone's list of the 100 Best Songs of 2007.