The below description is taken from LEGO.com.
They call it a rock because it rocks, baby!
You’ve heard of hard rock? Well, check out the rock-solid Rock Star! He sleeps on a bare bed frame with no mattress. He takes the padded insoles out of his shoes. He uses the strongest hair gel ever invented. He only eats stale bread rolls (with rock candy for dessert). And his guitar is carved out of a single huge diamond.
The Rock Star rose to rock stardom with his mega-hit song, “Brick Wall Baby.” The record went platinum right away, but that just wasn’t hard enough for him, so he had it recast in titanium carbide. Now he’s looking for something even harder that he can use to make a completely indestructible tour bus for riding between concerts!