Unusual rocks

[Jimmypop]

Here are both sides of two sandstone rocks found together in a small field that has produced a lot of native american artifacts. I have found no others like them. I have also found a lot of manos with some having a dimple in the center of the smooth side indicating use as a hammer. Enough background. Now my question. Do these rocks look like anvil stones or just naturally occurring rocks with the indentions.

 

[ghadarits]

I’m not sure what they are but one appears to have a lot more recently made dents, the edges are still sharpish if you know what I mean.

 

[Jeepnfish]

Nutting stone?