Answer:
You throw me out when you want to use me and you take me in when you don't want to use me. Who am I?
What holds names and memories which are not its own?
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
I heard of a wonder, of words moth-eaten. That is a strange thing, I thought, weird. That a man's song be swallowed by a worm. His blinded sentences, his bedside stand-by rustled in the night - and the robber-guest. Not one wit the wiser. For the words he had mumbled.
This thing runs but cannot walk, sometimes sings but never talks. Lacks arms, has hands; lacks a head but has a face.
You use it between your head and your toes, the more it works the thinner it grows.