It doesn't happen often...
... but I stumbled upon a hand blown Crown Glass "bullseye" window pane this AM! The center area where the punty was connected was considered an imperfection at the time and typically resmelted or used in a low end applications like a rear transom.
This window, however, is front and center on a late 19th century Victorian. I have only seen 2-3 in St. Louis over the last 15 years so I had to share. So rare, so interesting. ❤