Premise: Mark Arm (born Mark Thomas McLaughlin, February 21, 1962) is the vocalist for the grunge band Mudhoney. His former group, Green River, is one of the first grunge bands, along with Malfunkshun, Soundgarden, Skin Yard, the U-Men, and others. He is also the manager of the Sub Pop warehouse and previously worked at Fantagraphics Books.
Hypothesis: Mark Arm has been in Mudhoney and Green River.