A curious thing about that metallic rock.
Let's assume that it is an iron-meteorite.

If such an iron-meteorite fell to Earth, for example, and survived the passage through
our thick atmosphere, it would have slowed down to a point where
a crater was unlikely.
I'm assuming it weights a couple of hundred pounds [Earth weight]

But?...If that iron-meteorite, is a primary impactor, and fell through a thin martian atmosphere to the surface less than say 100 Myears ago, why no crater?

It should have retained its hypersonic or supersonic speeds at the bottom of a thin
martian atmosphere and slammed into the martian surface at a good speed.

But if it fell to Mars hundreds of millions or billions of years ago, when there was still
a thick martian atmosphere, why haven't acids and oxygen from the "wet" Meridiani
epoch eaten it away by now?