Not having any metal (as already related), axes were made of chipped flakes of obsidian (a glassy, flint-like volcanic stone) or of other stones ground to a sharp edge, or of hard, sharp-edged bivalve shells, or sharp-edged bones from the flattened spine of the tortoise or turtle. Terrible instruments for slaying and beheading were devised from the lower jawbones of large fishes, with saw-like rows of recurved teeth; or by implanting razor-edged sharks' teeth into the sides of wooden swords. Daggers with saw-like edges were made from the spines of the ray or skate, as well as from very hard wood rubbed down into a sharp cutting edge by sharks' skin. Spears and pikes were also made from hard wood and sharpened by burning the point in the fire. Or the point of the spear was made from the bony spines in the tail of the great Ray fish, or the wooden haft of the spear was fastened to a sharpened stone or obsidian blade by means of resin. Bows and arrows were in use nearly throughout New Guinea and most of the adjacent island groups; also in the New Hebrides. But they had not been introduced into New Zealand, and had fallen into disuse in most parts of Micronesia and Polynesia, though they were originally used by all these Oceanic peoples. In the eastern Melanesian islands slings were employed to hurl stones. Clubs and throwing sticks were common Papuan and Melanesian weapons, some of the former as executioners' weapons being fitted with stone heads. Shields scarcely penetrated to Polynesia, but were much developed and most fantastically carved and painted in New Guinea and some of the western Melanesian islands. In the northern parts of Oceania armour made of fibre, cord, or matting, and helmets of fibre, wood, or basketwork were worn, but more for ornament than to shield the head.