Thanks Jens, Jim,
Jens, you're close with one element, but not exactly. I'll post the answer if noone guesses right. I think these minor details and the messages the makers and patrons of these times were trying to convey were more meaningful than we think and their eyes were trained to recognize and understand these details on a different level. Thus, it is important for any art connoisseur to be able to recognize them to get closer to their intended meaning.
Kubur, by all means, the horses, how could I forget
I recall seeing only one Mughal all-steel horse head in one of the books, but think it was all-silver; and many ivory and jade ones of course, but never in any museums or collections I saw all-metal one.