obviously an add-on -- my example of that camera -- it is an 80 or 80A -- lacks a bell. Is it a timer of some sort? You had to pull the print and time it for 60 seconds before the print was done and you could open the door and peel it off. A timer is more convenient than counting or pondering your wrist watch.
Maybe if you turn the housing it will start to tick. If you turn it counter-clockwise the whole shebang will probably unscrew -- there's a tripod mounting hole under there. The type of camera -- 80 or 80A -- is engraved adjacent to the tripod hole. If you open the back hatch it should tell you what model it is as well, although mine says 80A on the front and only says 80 inside.
I remember as a kid watching a salesman try to sell one of that very model to my dad, who declined, but I thought the whole thing was magical, which is why that's the only polaroid I didn't give away when i was thinning out the herd.