Don't feel bad. I think I owned that album for about ten years before I realized it was an ear. And the only reason I realized it was because I read something that referred to it as an ear. :
My least favourite might be "Dawn of the Black Hearts", a bootleg live album by Mayhem. Their ex-singer called Dead took a shotgun to his head and killed himself. The ex-guitarist Euronomys (who later got killed by "The Count") found Dead's body and took a picture of it .. that picture ended up on the cover of the bootleg. Or so the story goes.
Obviously I won't post it here because I consider it snuffy, but if you really feel a need to check it out, they have the cover on the bootleg's wikipedia article.
Hell yeah! Not having seen the cover, if you hear the song "holy diver", you might think it's just a metaphor .. But on the cover, the holy diver is illustrated as a priest chained up and thrown into the sea by the Dio devil figure. Awesome!