As it happened, one of Hall's contemporaries, Jacques Plante of the Montreal Canadiens, began getting the notion that being playing goal without a mask was a bad idea. Ever creative, even as a junior player, Plante began experimenting with the idea of a face protector.
Now, all hockey goalies wear masks. Moreover, all college hockey players wear masks and the vast majority of professional players wear visors. How would we predict that Jacques Plante's idea would become the initial object? Also, is it a terminal object too? How should we construct a meaningful category to model that?