[Futbowl]

I know that there are many Kellogg’s variations depending upon the year but I came across one I have never seen before and was curious if anyone has ever seen this. The card is a ‘76 Greg Gross #56, which has a known variation on games played but this is a different one. Look at the back of the card just to the left of Greg’s photo. What is that? I’ve checked all of other ‘76’s and did some research and can’t find anything like it. I thought it was just an artifact but the circle is perfectly round. It looks like it belongs there. Anyone have an idea of what this is? I’ve included a close up too.