I tried to match up a couple Pestles from Robert Converse's book 'Ohio Stone Tools'. If you Ohio guys have a copy please read about Conical Pestles, and Mortars. Here is what he says
Time period or Culture: Archaic
The Conical Pestle is virtually the only variety of pestle found in the Ky. Archaic. Conical Pestles are not as common as other varieties in Ohio.
These tools are rarely well made and seldom show the polish or fine workmanship associated with other types. Many examples do not have the pitted concavity in the base.
Usually CP are short, stubby, and rarely over 4 or 5 inches in length.
A wide variety of materials is present with granite, quartzite, and other crystalline stone predominating. Some specimens are weathered almost beyond recognition.
I hope I haven't done anything wrong by using Mr. Converse's pic and discription of Conical Pestles. It seems it was the only way of helping with my point. If you don't have a copy of 'Ohio Stone Tools', get one from ASO. They are only $8.00. A very informative read.
My 2 rocks are on either side of the bottom sketch. There were sketches of 3 CP on that page. I thot they matched up well.