Conversation so far:
How did Celtic Frost get started?
Celtic Frost's frontman Tom Warrior with Steve Warrior on bass formed one of the earliest extreme metal bands, Hellhammer, in 1981
Who else was part of the band Celtic Frost besides Tom Warrior and Steve Warrior?
Martin Eric Ain
What instrument did Steve Warrior play in the band celtic frost?
bass
Who else was in the band celtic frost besides Steve Warrior?
Tom Warrior

Question: What instrument did Martin Eric play?
Self-contained rewrite: What instrument did Martin Eric play for the band Celtic Frost?