1.解剖学证据

The shell of a snail is made up of calcium carbonate. The shell becomes very strong and remains that way as long as the snail consumes a diet that is full of calcium. Without it the shell will start to crack. Since the rest of the body is very soft and slimy, they must have a hard shell if they are going to survive the elements in the world around them.The shell is s safe haven for the snail to reside in. When it senses danger around it, putting the whole body into the shell is the line of defense. You will also find that the snail spends a great deal of time in the shell when the weather is very hot and dry. Otherwise their moist bodies will dry out.-http://www.snail-world.com/Snail-Anatomy.html

 

由此来看蜗牛的螺旋形外壳是能够耐受很大压力的，不知道同样是碳酸钙外壳，鸡蛋壳和蜗牛壳哪个的耐压能力更强大一些。

2.介绍一个网站专门论述软体动物的外壳的