Best medium riddles with simple answers

I am covered in feathers or foam, yet I have no wings and cannot fly. I am the only place where you can lose and find your mind at the same time.

I am the place where the earth meets the sky and the water kisses the land. I disappear twice a day, only to return again. What am I?

I have a headboard but no brain, and a footboard but no toes. You visit me to travel to worlds that don't exist. What am I?

I am a giant sandbox built by nature. I have a coat of gold and a hem of blue, and I am the favorite place for a holiday view. What am I?

I have billions of tiny stones but no mountains. I have waves but no hair. People lie on me to feel the warmth of the sun. What am I?

What is the ancient invention that allows people to see through walls?

What is more impressive than a talking dog?

What is a fish without an eye?

Where do fish keep their money?

What goes up and down the stairs without moving?