The walls of some algae differ, e. g. the silica boxes enclosing diatoms, and the calcareous layer on the cell walls of calcareous algae.

一些藻类的细胞壁的化学成分有所不同，例如硅藻属的细胞壁含有硅化物，石灰质藻类的细胞壁含有钙。

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Protected surfaces can build up a layer of off white calcareous deposit which will be difficult to remove.

受保护的表面能够形成一层灰白色的钙质沉着，这是很难去掉的。

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