Unusual artifact

My son found this stone while we were hiking in Valley Green this summer. It is smooth to the touch, and features two holes, one on each side, neither of which perforates the stone. Some thoughts as to what it might be: a grommet-stone for starting fires, a "nutter" for cracking nuts, an unfinished fishing net weight (unlikely given the location....net-fishing in the Wissachickon won't get you much), or an incomplete amulet?