What Am I Riddles

Question: Round like a apple, deep like a cup, but all the kings horses can't pull it up.

What is it?

Question: What is brown or silver, has a head and tail but no arms or legs?

Question: What has a foot but no leg?

Question: I can be sun,
I can be sand,
and I can be bird.

What am i?

Question: A thousand wheels, but move I do not.
Call me what I am, call me a lot.

What am I?