LOL from me too. I did the exact same thing years and years ago, before I knew anything quilting related. I brought home a straight stitch black Singer, and absent mindedly started oiling and cleaning and found one of those things in the feed dogs, and wondered "why don't all machines have this protective stuff in them"......I guess I'll have to go out to my sewing room and check all my old Singers to see if I ever came back to it and cleaned it up.