Knocking sound from rear right of my Audi A4 B7 2005
 

Guys I seriously need an opinion.

I had this knocking sound for a hell of a long time and it irritates me to death. Each time I hit a road with little bumps etc I get this metal to metal knocking sound.

Today I jacked the car and did a little inspection.

I found the following. See the picture. What precisely is this? Can this may be the root cause of my knocking sound?

Not sure what the part is, but to me it looks like the bushing is wore out and will need replaced. Maybe the strut? Check all other suspension components and the shock absorber as well. Anything that looks out of whack like in that picture, likely is out of whack. There should be no play in anything, should be tight.