The circles that Tang Tang is drawing are not balloons that have floated in from outer space. They are hitching stones, frequently found in ancient ruins. The short lines inside the circles are grooves that people of antiquity carved with stone axes. Ropes or fishing nets were tied to these grooves for use in catching fish.
棠棠畫的圈圈可不是外太空飄來的氣球，那是考古遺址裡常發現的「網墜」﹘﹘圖中的短線便是遠古人用石斧刻出來的凹槽，用來綁繩索或漁網，捕魚用的。