A few millimeters of colored beads, after soaking in water, can quickly become large beads with a diameter exceeding 1 cm, and even produce small "beads". Such "magical" things naturally attract many children. Recently, many primary school students have become popular in raising "water sprite".

This transparent bead, the size of a rubber ball, is mainly red, yellow, blue, green, purple, orange, black, colorless and cyan, which is very eye-catching. They are packed in small plastic bags or small glass bottles. There are about 15~30 balls in each bottle, and the price is 0.5~ 1.0 yuan, because it will be found when put into water.