There is an exoskeleton on the surface of the cicada's body, which can protect and support the soft internal organs, prevent the evaporation of water in the body, and better adapt to life on land. The exoskeleton cannot grow with the growth of the insect's body. , there is molting during the growth and development process. The cicada slough is the exoskeleton of the cicada.

So the answer is: exoskeleton; growth.