Prehistoric hammerstones, sometimes known as mullers, pounders, or mauls, are supposed, as the name implies, to have been used as hammers. In the case of those made from flint nodules they present an unmistakable surface which consists of the heads of hundreds of small cones of percussion, and of angular fragments of broken, intersecting, cones, the whole being the result of a long, and continuous rain of blows, each of which affected but a small spot of the surface, and caused by the nodule coming into sharp contact with a surface nearly as hard, or of equal hardness, to the flint itself.