Answer:
This is a shape and a symbol that we literally cannot live without. What is it?
He's small but he can climb a tower.
When a doctor hits you with a hammer he is testing this
Even if you throw it away, it still comes back.
It's been around for millions of years, but it's no more than a month old. What is it?
I am all around yet to me you are half blind. Sunlight makes me invisible and difficult to find.