Not Shiny
Some eroded and knobbly rocks with pitted textures, but Mars has plenty of those, as have many dry environments on Earth - the weakest minerals wear away faster and leave holes that get enlarged*. These are commonly mistaken for the holes left in a conglomerate when individual pebbles weather out, but in that case there would be a pile of pebbles around the rock.
* some of the holes may be original or enlarged vesicles - gas bubbles in a solidified lava.