Does Acellular Dermal Matrix became absorbed by the body, or does it stay put but integrated into the body?

I had my implants changed 6 months ago, went a size up, so pockets had to be made larger. I had a Bovine ADM sling in one breast that was placed after I bottomed out after a car crash. Now I can feel that breast sitting lower again, and I can feel something at the bottom of that breast! He admitted he forgot about the sling, and cut right through while making the pocket bigger, but that it would be gone by now, told me it can not be the sling as it would be absorbed by my body??