Flat faced rock tool?

[Charles Jones]

I walked by this rock several times over the years before I really looked at it. It weighs about 4#. One face is very flat and smooth, and has a dimple pecked in it. It appears to be a fine grained gray granite. Found in a known inhabited area with artifacts from several periods. Found in Fayette County Illinois. Looks like it would have been a useful stone for processing food and maybe pounding on things.
I really enjoy finding and looking at the everyday tools people used.

[gregszybala]

Hard to see the dimple in that lighting.

[Hal Gorges]

Hey Charles, a tip on photographing depressed areas..Tilt the rock till the shadows show the most character.if that makes any sense.

[Charles Jones]

The dimple is rather shallow and hard to see, but can be felt.

[SurfaceHunter]

Probably a anvil or a nutting stone looks like a type of rock they would of used for something