They found that the brown shell is made of an array of grooves that split sunlight into diverging beams.
他们发现棕色的外壳由大量的沟状结构组成，它们能把太阳光转换成散射光线。
2
In ancient times, before important activities were held, a wizard would roast a tortoise shell and then practice divination according to the way the lines split on it.