船底覆盖着一层由贝壳和藻类形成的坚硬硬壳。

The bottom of the boat was covered with a hard ___encrustation of shells and algae.

长时间浸泡在矿泉水中会导致石头表面形成一层硬壳。

The ___encrustation of minerals on the stone surface occurs after prolonged soaking in mineral water.

这个花瓶表面的金色装饰层非常精美。

The vase has a beautiful golden ___encrustation on its surface.