Answer:
What looks back but cannot see?
Round as a button, deep as a well. If you want me to talk, you must first pull my tail.
Mobsters judge the quality of a vehicle by the size of this
There are millions of me. I am very small but when moving fast I am deadly.
Walk on the living, they don't even mumble. Walk on the dead, they mutter and grumble.
It's what light turns into in the night
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?