I dont know much about this fossil, but it was found in a potato field, in central WI. i believe that we are near the shore of what used to be glacial lake wisconsin. as the name implies it could have been brought here by a glacier, or was here because of the lake. if anyone has any insite into this as to what kind of shell and/or origin. i hope the picture comes though. the big fossil is about nickel sized, looks like mostly limestone.

http://discussions.travelchannel.com/eve/forums?a=gettemppaim...3FEA5E.jpg&isthumb=Y