Iron (Nicky Romero and Calvin Harris song)  "Iron" is a song by Nicky Romero and Calvin Harris. The song was released as a single, via Beatport. It became the second single to be released through Romero's label Protocol Recordings (after "WTF!?" with ZROQ), and the first single from the label to reach number-one on Beatport. A shortened version of the song was later included on Harris' third studio album, "18 Months" (2012). The majority of the song has an upbeat electro house style until vocals from Harris come in. When the vocals do come in, the background tune is just a piano being played until Calvin Harris sings ""Our hearts will never be the same again"". After this happens, the tune becomes upbeat again.