Although the coral looks hard, it is very delicate.

虽然那珊瑚看起来坚硬，它其实非常易碎。

《柯林斯英汉双解大词典》

So we have been fairly thorough in our discussion about coral reefs, which of course are prominent, oceanic features made of hard limestone skeletons produced by tiny coral animals.

我们对珊瑚礁的讨论已经相当深入了；显然，珊瑚礁具有显著的海洋特征，由小型珊瑚动物制造的石灰骨架构成。

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By building complex, three-dimensional structures that expose the hard rock beneath the sand, Miller said, red grouper create an environment in which seaweed, coral and sponges can thrive.

Miller说通过建著复杂的空间结构使沙子底下的硬质岩石暴露出来，赤点石斑鱼创建了一个海藻，珊瑚和海绵可以繁荣生长的空间。

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Each coral polyp releases a hard calcium carbonate skeleton that serves as a base.

VOA: special.2010.08.10

Bioerosion: process by which animals, through drilling, grazing and burrowing, erode hard substances, for example rocks and coral reefs.

UNESCO: L O S S A R Y

The coral turns white when it expels the minute organisms that live within its hard limestone core.

ECONOMIST: Pink coral into grey rubble

Coral reef: complex tropical marine ecosystem dominated by soft and stony (hard) corals, anemones and sea fans.

UNESCO: L O S S A R Y