Dissolved in the ocean. 从而长出贝壳

85. They reveal nearly two billion years of the earth's history.
    它们揭示了近二十亿年的地球历史
86. Once upon a time, the grand canyon was a sea inhabited by microorganisms.
    从前 大峡谷曾经是微生物居住的海洋
87. They grew their shells by tapping into carbon from the atmosphere...
    他们通过吸收溶解在海洋中的大气碳元素
88. Dissolved in the ocean.
    从而长出贝壳
89. When they died, the shells sank...
    他们死去以后 贝壳沉没
90. And accumulated on the seabed.
    并沉积在海床
91. These strata are the product of those billions and billions of shells.
    这些地层便是数以亿计的贝壳的产物

来自《家园 第一部分 Home Part1》第 88 行