Sorry to get your hopes up with the grandiose title, but I just wanted to post something interesting I noticed today. It may have already been posted in that one old thread that talked about a lot of things like this.
What I noticed is that the song of the final Bowser on Super Mario 64 (32. Ultimate Koopa on the OST) has the same chord progression as the SMB3 Underwater Theme (which, after all, is kind of like the beginning of the SMB1 Underwater Theme).
Listen for it especially in the opening fugue part.
“I’m a stupid fatty and I love to play with my Easy Bake oven.â€