:? Well, actually, I do know what it is for now. And I think it is majorly cool. I did look at the JoAnn's link and didn't see it on there. I really don't know how to describe it other than how I did earlier. And I'm real sorry, but I have a terrible time downloading pictures to show ya'all what it is. But all my stuff show's it's called a "Cloth Guide".
I found a link, the thing I have is the one in the dead middle of the top picture. http://www.sewitgoes.net/smuse/attachments/seamguide/atseamguid.html