I didn't know where to go for something like this exactly, but it seems the internet has landed me here, and after looking around this actually might be the best place for it.
Anyway, I remember long ago (read: about 13 years ago) being introduced to a canon (possibly, a fugue) by Mozart (possibly Bach) in C Major (or Minor). I can hear it in my head, but because I have so little information on it, I can't remember much else.
I do know the first few notes. Although I have no way of metering here, as long as you hear the notes played, you'll either know this piece or not. It's very distinquishable. It is NOT Pachelbel (although there seems to be a million videos of Pachelbel online):
D A F EDFEDC#E A D A E A F EDE A D ADE AEF E DE A
So, does that sound familiar to anyone? Also, I believe it was originally written for the organ.
If anyone thinks there's a better place for me to ask this, please suggest it as well.