It's made of layers and layers of a different hard material called nacre.

它由一层又一层不同的坚硬材料制成，这种材料叫做珍珠层。

The sac coats the irritant with layers of smooth nacre, also known as mother-of-pearl.

珍珠囊给刺激物外裹上一层层光滑的珍珠层即珍珠母。

The growing pearl rotates itself, which allows the nacre to deposit evenly over its surface.

逐渐变大的珍珠会自己旋转，让珍珠层均匀地沉积在表面上。

The large center is the manmade irritant placed in the shell to encourage nacre formation.

中间的大块是为促进珍珠质形成而放入贝壳中的人造刺激物。

A pearl's motion influences its nacre coverage, and thus its final shape.

珍珠的移动影响其珍珠层覆盖，继而影响最终形状。

This triggers the oyster's defense response, and it starts coating that piece of tissue with nacre.

这触发了牡蛎的防御机制，它开始用珍珠质包裹那块组织。

The quality of a pearl's luster is influenced by the layers of nacre that coat the center.

珍珠的光泽质量受覆盖在中心的珍珠层的影响。

The bay blossoms were nacre, with diamond drops at their centers.

月桂花是珍珠质的， 中心有钻石滴。

The uniform layering and brick-like structure of nacre is key to its signature iridescence.

珍珠层的均匀分层和砖状结构是其标志性彩虹色的关键。

But one form of aragonite is stronger and more versatile than the rest: nacre.

但有一种文石比其他文石更坚固、用途更广：珍珠质。