堆沙蠕虫分泌出一种胶状物将沙石粘合在一起形成壳装，这一点类似于淡水石蛾的幼虫。

Instead, it secretes a glue and USES this to stick bits of sand together to form its casing, in the way that a freshwater caddis fly larva does.

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在5亿年前的寒武纪，似蠕虫生物逐渐演化成似鱼生物。

During the Cambrian period, 500 million years ago, worm-like creatures were evolving into fish-like creatures.

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