Metronome (Mario's Time Machine)
From the Super Mario Wiki
The Metronome is an item in the SNES version of Mario's Time Machine. It is small and brown, with a black pendulum that goes up its front. It is given by a neighbor of Ludwig van Beethoven in Vienna, who hands it off to Mario soon after he is given the Fan, since he is tired of its continuous ticking noise. It can be given to the owner of a nearby music store who is looking for new merchandise. Once the shopkeep has the metronome, he thanks Mario for the item but then gets ready to leave for an appointment with his optometrist (at which point he can be given the Monocle).