That is a handgathered slag.
Could be one of the earliest American machine-made marbles. Quite possible M.F. Christensen.
The little indented crease is called a "cutline". The other side has what we call a "nine and tail". (I see you mentioned the nine.) What you're seeing as a pontil might be a chip or an airbubble.
The 9 and tail is where a little extra bit of glass was quickly whirled around the end of the marble before the person snipped at the cutline and dropped the molten ball onto the marble rollers. So in the general course of things no punty would have been touching the marble at that particular spot on the end.
If it's MFC, it dates back to between 1903 and 1917.
Other companies also made handgathered marbles, but no one will call the marble cops if you assume MFC here.