What do snakes periodically shed as they grow?

Skin

Who is the resident bully next door in the original "Toy Story"? Who struck the Nile river, turning it into blood? Which amphibian breathes completely through its skin, having no lungs at all? What famous American poet wrote the poem 'A Visit from St. Nicholas' commonly known as 'The Night Before Christmas'? In Fallout 3, your character starts life in what unique structure?