Congrats, and I'm so glad it finally arrived!
Personally I don't believe we'll ever find out what exactly that bowl shaped iron item originally was. As I told you before I don't think it has anything to do with the process of casting iron as the object itself seems to be cast, telling from the porous surface and the relative thickness of the iron. I would expect such an item to be of thin wrought iron. Even if it were so, and the long handle were missing, it would not belong to a wrought iron cannon ball.
As I stated when authoring this thread I own the only other sample known so far. We only know of their existence and their makers, the Pögl workshop in Thörl near Innsbruck/The Tyrol, where the Maximilian main armory was 500 years ago, by written sources when the - then king - Maximilian I ordered thousands of these wrought balls because he believed in their greater effect as compared to cast balls.
Though I am not much of an ordnance expert, I think calling it a three pounder ball would fit. In this case I would attribute it to one of the smaller types of Maximilian artillery, e.g. a wroughht iron falconet.