小蜗牛问妈妈:为什么我们从生下来,就要背负这个又硬又重的壳呢?妈妈:因为我们的身体没有骨骼的支撑,只能爬,又爬不快,所以要这个壳来保护!小蜗牛:毛虫姐姐没有骨头,也爬不快,为什么却不用背这个又硬又重的壳呢?妈妈:因为毛虫姐姐能变成蝴蝶,天空会保护她啊。小蜗牛:那么蚯蚓弟 Small snail asked mom: why we born from, we must carry the hard and heavy shell? Mom: Because our body without bone support, can only climb, climb unpleasant, so the shell to protect! Small Snail: Caterpillar sister does not bones, but also climb unpleasant, why not back this hard and heavy shell? Mom: Because the caterpillar sister can become a butterfly, the sky will protect her ah. Small snail: then earthworm brother