Answer:
What is pronounced like one letter, written with three letters. And belongs to all animals?
Take one out and scratch my head I am now black but once was red.
The stack just might be sent all over. Full of what's new, yet it's nearly obsolete.
I open wide and tight I shut, Sharp am I and paper-cut fingers too, so do take care, I'm good and bad, so best beware.
Hoofed frolicking.
I have two eyes in the front and a lot of eyes on my tail
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?