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。

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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.

在古代，每当举行重大活动之前，巫师都要烧烤龟甲，然后根据龟甲上爆裂的纹路来占卜吉凶。

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