Shields protect the warrior against weapons which include bone or bamboo-tipped arrows, sharp wooden spears, stone axes and bone knives. They come in all sizes from large planks that a bowman or spear thrower can shelter his whole body behind, to smaller breastplate ones. Lightweight wood, like the roots of mangrove trees, are used for these shields. Designs of these shields can vary from tribe to tribe. Geometric designs are common but clan and ancestor faces or wildlife totems may be used too. Although used primarily as a defence tool in wars, shields still hold an important and powerful role in ceremonies.