We will see what Robert says. I could not locate the shape in the drawings I have, but that does not rule them out in my mind. I also looked at the pontil marks on mine again, and a couple of them are cleaner than most of them. It is on examples which have more clear or translucent glass at the surface. There appears to be a small space of clear at the rim of your example in the first pic.
Either way, it is an interesting piece of glass...
Craig