Super Mario 64 didn't skimp out on small details -- take, for example, the penguins in Cool Cool Mountain. They do more than just provide you with stars, you know.
GameXplain breaks down some of the neat things you might've missed about 'em, like how the baby penguin cutely mimics Mario. Aww. Maybe I wouldn't have cruelly gone out of my way to toss the baby penguin off of the map after I got the star from its mum had I known it did this!
Cool Bits - Super Mario 64's Penguin Secrets [GameXplain]