These curious “incised” limestone rocks from the Panther Springs Creek site in northern Bexar County are thought to be shaft straighteners that were heated slightly and used to help shape and straighten wooden dart shafts. Never common, these artifacts have been found here and there across the region, although they are easy to miss—in the ground, they look pretty much like a cooking stone. From Black and McGraw, 1985, The Panther Springs Creek Site: Culture Change and Continuity within the Upper Salado Creek Watershed, South-Central Texas. Center for Archaeological Research, University of Texas at San Antonio.