Sea urchins are perhaps best known for their armor of spines. But their mouths may be even more daunting-urchin teeth can literally chew through stone without getting dull.

也许关于海胆，人们知道得最多的是它们的棘刺盔甲。但是，它们的口器可能更令人望而生畏——毫不夸张地说，海胆的牙齿可以把岩石咬碎，却永远不会变钝。

youdao

But their mouths may be even more daunting-urchin teeth can literally chew through stone without getting dull.

但是，它们的口器可能更令人望而生畏——毫不夸张地说，海胆的牙齿可以把岩石咬碎，却永远不会变钝。

youdao

Stone tools abound, but human bones from other Asian sites are almost as rare as hens’ teeth.

石制工具大量出土，但在亚洲其他地方发现的人类骸骨几乎是凤毛麟角。

youdao