Chris Martin served as a music guest during Saturday Night Live's first "At Home" episode on April 11.In a live black-and-white recording, the Coldplay frontman performed an acoustic cover of Bob Dylan's "Shelter From the Storm." Martin delivered the classic 1974 track alone surrounded by instruments and with the words "Entrance to Trains" written behind him, likely a reference to SNL's Grand Central-themed stage in New York.His song choice was especially appropriate given that most people