Answer:
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair.
I am in the past never in the future. I don't exist but have existed. I saw what you saw and that is what I will ever see.
Soft, hairy, from door to door. I am the pet that always stays on the floor. What am I?
The more you look at me The less you see.
An open ended barrel I am shaped like a hive. I am filled with the flesh and the flesh is alive.
A little house full of meat, no door to go in and eat.