who knew?

You learn all sorts of fascinating things in law school. Today in Civ Pro II I learned from the professor that when a judge in Pennsylvania hears an admiralty case he puts a big oar on the bench in front of him to make sure everyone in the courtroom knows he's using admiralty law instead of 'regular' law.

It brought all sorts of questions to mind:

Does the judge bang the oar instead of his gavel?
Is it a special oar or will any oar from any old rowboat suffice?
Is the professor sure it's an oar and not a paddle?
Isn't an oar slightly obsolete? I haven't taken admiralty law but I doubt that these days many admiralty cases come up where one of the parties was rowing.