Something's wrong with this brake part.

[desert-rat]

So I was able to get some pics of rear drums from a few members. I see a problem here. Why is this piece shaped differently?? And as you can see, somehow it came loose and worn through thanks to the axle. Wrong piece?? I repositioned it and it came loose again. What's going on here?? And the shoes seized to the drums but that's for another thread.