英语语法分析

The foraminifera in the core samples were most abundant after 1950, when farmers began using some fertilizer, which is rich in nutrients.

核心样本中的有孔虫在1950年之后最多，当时农民开始使用一些营养丰富的肥料。

The fossils buried in Pleistocene and earlier ocean sediments were of foraminifera—small, single-celled marine organisms that secrete shells of calcium carbonate, or calcite.

在更新世和更早的海洋沉积物中埋藏的化石生物属于孔虫类生物，它们是微小的单细胞海洋生物，其分泌的硬壳由碳酸钙和方解石组成。

But these shells are absent from the foraminifera found in Challenger Deep.

但是在查林杰海渊发现的这些有孔虫却没有这种甲壳。