The head looked familiar, and the unicorn on the link Laurie posted looked extremely familiar. Checked, and I have a music box by them. Plays “All I Ask of You” from Phantom of the Opera. Mom gave it to me years ago for an exmas present.
It has gone off without cause once before as well. Sometime after my mom died. Was just laying in bed trying to sleep and it went off for about 5 seconds. I never play it (once in a rare blue moon) so it had no reason to start up.
If it helps at all, I do remember that I originally pointed the music box out to my mom, and we were at a drug store (Osco at the time, now CVS). This was eons ago though.