Answer:
Once you know it exists, it no longer exists. What is it?
Something we eat, and misspell as meet.
I am the red tongue of the earth, that buries cities.
What can you hold in your left hand but not in your right hand?
I occur twice in eternity. And I'm always within sight.
As round as an apple. As deep as a cup. All the king's horses can't pull it up.
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?