Answer:
What gets closer when you blink?
I usually wear a yellow coat. I usually have a dark head. I make marks wherever I go.
What has three ways out and just one way in?
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
An open ended barrel, it is shaped like a hive. It is filled with the flesh, and the flesh is alive!
Break me and I am better immediately set and harder to be broken again.