a little piece came off my Razr V3 - what is it?

I opened the fone to change the battery ...just looking to the right of the sim card in line with the metal retaining bar there is a golden piece of metal which sticks out of the plastic via a small 1mm wide 1mm high slot ...this bent metal tab had one end which was sticking out ...while putting it back under the plastic on the end facing the sim card, a little of it broke off (<1mm) ...it went back in and looks OK but what is this thing and what does it do? The fone works fine.