这里有个例子，一种牡蛎状双壳贝，进化出越来越趋螺旋状的外壳，直到该物种灭绝前，其外壳已经几乎打不开了。

There is a case of an oysterlike bivalve that evolved a more and more spiraled shell until, just before extinction, the valves could barely open.

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但是没关系，因为您肚子里能分泌一种叫龙涎香的蜡状油脂物，能够保护您的内脏不被内壳诸如此类尖锐的东西所伤。

But it's OK, because your belly produces something called ambergris, a waxy oil that protects your insides from sharp beaks and whatnot.

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最后是那些为数甚多、通常低于海平面的火山，它们在板块分离、新壳产生的延展脊状突起上形成。

Finally there are those-a great many, but normally deep under the ocean-formed at the spreading ridges where tectonic plates pull away from each other and new crust is formed.

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