phragmoconch

例句：

1. 1. The spider's web is suspended from the ceiling by a delicate phragmoconch.
   蜘蛛网由一个精巧的胸甲壳悬挂在天花板上。
2. 2. The phragmoconch of the turtle shell provides protection against predators.
   乌龟壳的胸甲壳提供了对捕食者的防护。
3. 3. The phragmoconch of the octopus is used for its unique coloration.
   章鱼的胸甲壳因其独特的颜色而受到青睐。