Ohmigod!! You have an extremely rare and valuable inverse capacitance recapitulator for discombobulating the flux modulation associated with right hand turns and the flashers accidentally indicating left!!!!
Actually I have no clear idea, though Justin's suggestion of buzzer might be pretty close. I looks like a very early piezo type, with then reed spring maybe making contact with, and using the mylar looking clear cover as the sounding board. The coil underneath, associated with the circuitry and possible contact make and break of the reed spring make it seem more likely. Though the only fly in the ointment is the extra two wires coming out the back.
Bill..................;-)