It's probably ordinary basalt
I'm also no geologist. The rock is probably basalt with gas pockets that formed over 3 billion years ago. Millions of years of "sand" and dust abrasion has worn it down to its current form. There is literally nothing like this on Earth. In the same time span on Earth, a rock like this would have been subducted back into the mantle at least twice and dissolved to liquid multiple times. Our terrestrial intuition is inappropriate here. That was the point that I was ineptly trying to make.
Gary