Mike Ratledge, keyboardist and founding member of the English rock band Soft Machine, has died at the age of 81. The musician’s death was confirmed by former bandmate and current Soft Machine guitarist John Etheridge in a Facebook post, according to Louder.

Though the band had little commercial success, Soft Machine has been considered a revolutionary rock music act. Dave Lynch at AllMusic called the band “one of the most influential underground bands of their era” while Louder called Soft Machine “pioneers of both progressive rock and jazz fusion.