What is the square rods function, that fell out of the end of my distrubutor when I remove it? What is supposed to hold it in the end? Could it be the cause of the rattling I hear in the engine?

What is the square rods function, that fell out of the end of my distrubutor when I remove it? What is supposed to hold it in the end? Could it be the cause of the rattling I hear in the engine?
The engine's cam drives the distributor.
The distributor drives the oil pump.
That shaft drives the oil pump drive, and, yes, could cause a rattling noise.