It varied in size and in shape; from a fusiform to conical shapes; it is made of light or hard lumber, and dried seaweed roots were used in ancient times.
紡錘形から円錐形まで形状・大きさとも一様ではなく、材質は軽量、硬質な木材など、古くは海藻の根を乾燥させたものが使用された。