Answer:
We are all around, yet to us you are half blind. Sunlight makes us invisible, and difficult to find.
What has a bell but isn't a church. Is full of air but is not a balloon?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.
You can see nothing else, When you look in my face, I will look you in the eye, And I will never lie.
They belong to me; they belong to you; They can make you feel happy or make you feel blue; They never end until the day you do.
Before I grow I'm small. When I'm old I grow tall. When I die I give a mighty fall.