"A few days after the album [Songs of Innocence] was finished, I thought Iris shouldn't be part of the album. Even though the song is a beautiful tune and everything, I just thought it was going a bit far and it's not very punk rock, singing about your mother."
did you know
The lyric "3:33 when the numbers fell off the clock face" from Unknown Caller is a reference to the Bible verse Jeremiah 33:3. Bono refers to it as "God's phone number".