I actually just got back from watching Pirates 3 myself, and that
strange barrel organ/piano jumped out at me as well.  For those who
don't plan on seeing the film, it consisted of a large spring-driven
pinned barrel which struck or plucked a set of exposed strings as well
as playing a set of unseen pipes.

Incidentally, plot-wise it seems the organ was moved into position to
cover up the noise of the pirates breaking into the sub-level of the
bath house and later it functioned as a time-bomb when it's spring drive
wound down.

Ben Willis