Out here they are flat rocks that act like a surface to work on...usually smooth on one side and indented or chipped or scratched up on the other. kinda like the old fashion version of this...most likely associated with settled villages or seasonal camps, not an item particularly worked or important, easy to over look, easy to discard and easy to replace.
Interesting looking rock painter. No experience on it from me but looks like it was used for something maybe a nutting stone if it was found in my area
Well here's my thoughts on this one lol . I think these were earlier forms of a mortar . Just like a hoe you won't find a huge beautiful one on a later period sites . More farming bigger hoes bigger mortars