Mutual Core

"Mutual Core" is a song recorded by Icelandic singer Björk for her seventh studio album Biophilia (2011). It was written and produced by Björk herself, while programming and beats were made in collaboration with Matthew Herbert and the English dubstep band 16bit. "Mutual Core" is an uptempo experimental song. Its music includes Pipe organ, electronica-tinged sounds and features the Choir Graduale Nobili, the choir featured on Biophilia. The song's lyrics are a metaphor for human relationships, compared to the structure of the Earth and Plate tectonics. The song was well received by contemporary music critics, who praised its production and beats, moreover appreciating Björk's voice on the track.

As with all the songs on Biophilia, an app was made for the song, which features a video game in which the player have to move geological layers as an accordion to play chords. Though the song wasn't released as a single, a music video was produced, directed by Andrew Thomas Huang. The video was critically applauded and received further attention when it got projected for one month in Times Square in 2013, and then across the 7 continents. Björk promoted the song by performing it throughout her Biophilia tour.

Three remixes by Matthew Herbert, 16bit and These New Puritans were released as part of Biophilia Remix Series. The Matthew Herbert's and the These New Puritans remixes were later included on bastards (2012). In July 2012, the online music store Beatport announced a fan contest in which "Mutual Core" had to be remixed, to be released afterwards on a remix package.