海洋生物死亡以后，它们的尸体向海洋底层沉淀下去。

When they died, they sank to the bottom of the sea.

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浮游生物处于海洋食物链的最底层。

Plankton is at the bottom of the Marine food chain.

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浮游生物处于海洋食物链的最底层。

Plankton is at the bottom of the Marine food chain.

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