[ Upon hearing the musical statement, Rapture speaks up. ]

The symbol is nothing I recognize musically, not even from the sheet music I've seen over the years.

I'm only a bass player, but I haven't seen it for vocal or percussion either. The only thing I can think of is that weird shape on the body of a violin... but that looks more like a 'f' than a 'S.' Even then, that wouldn't be related to the piano, minus that they both require strings to be played.