sanding disk

Boogie Street's Mr Zip, an artist and blog pal in the UK, wrote this on my previous post called rust circle:

Lovely piece of metal, and I can understand why you've kept it for so long. When at university I picked up a sanding disk with black patches and scraps of paint attached, which I found similarly attractive, and it's been hanging on my studio wall ever since. I know it can be used in an artwork somehow, but have yet to find the right way. Meanwhile, I just enjoy it for its own sake.

And he kindly offered these images to me to put up here. Aren't they gorgoeus?! I can just imagine a future archaeologist excited by finds like ours.

Circles, especially man-made ones, have recently figured in some of my work, so maybe I was led to rediscovering my long-saved rust circle.... and receiving another from a reader! Anyone else have similar weathered treasures?