Martin Garrix and U2 released "Fireflies." The Dutch DJ and producer premiered it with U2 guitarist The Edge at Tomorrowland this month, sending crowds into a frenzy. "'Fireflies' has a very unique mood and it's a special song we started working on six summers ago," said Garrix, according to RTTNews. "It felt electrifying and very surreal to finally debut it at Tomorrowland with The Edge. Garrix produced "Your Song Saved My Life" for the Sing 2 soundtrack, performed by the rock outfit.