复数： urchins

To learn how urchin teeth stay sharp despite all that grinding , researchers analyzed the roughly 0.1-inch-long ( 3-millimeter-long ) choppers of the california purple sea urchin .

为了了解为什么海胆的牙齿不停地打磨岩石却不会变钝，研究人员对加利福尼亚紫海胆大约0.1英寸（3毫米）长的牙齿进行了分析。

Still , somehow , the negro and the urchin held him in a greater terror .

不过，不知为何，黑人和顽童们却更加畏惧他。

It grows like a sea urchin : long spines of ability radiate out towards specific needs and desires .

科技的发展就如海胆：能力像长长的脊椎一样向特定需求呈放射状。

Only three parts per million can kill sea urchin embryos , for example .

举例来说，仅仅百万分之三就能杀死海胆晶胚。

Adam was violent , and his cries and curses , his hard and brutal manner were the terror of the negro who passed at night that way , or the urchin overtaken by darkness on his road home .

亚当的内心充满暴力，他的漫天咒骂，他的冷酷无情，让夜晚走过那条路的黑人或是赶着夜路回家的顽童不寒而栗。