Fiat Shower Drain Plate 4.5 x 4.5 inch

If someone can tell me why such a simple thing as a shower drain grill has a name of a car manufacturer, please tell me in comments, I would be much obliged.

But this strange shape of the plate is sometimes referred to as 4.5 inch diameter Fiat plate or 4.5 x 4.5 inch Fiat plate, and neither name is exactly correct because it's neither square nor round. I tried to match the shape of the original plate (that got cracked and had to be replaced), but in the end did not quite get it, so some (min