Answer:
Large as a mountain, small as a pea, Endlessly swimming in a water-less sea.
There is a puzzle which can be asked all day with a different correct answer each time. What is the puzzle?
I tremble at each breath of air, and yet can heaviest burdens bear.
I am black when I am clean and white when I am dirty?
There are millions of me. I am very small but when moving fast I am deadly.
When is it bad luck to see a black cat?