Answer:
Tall in the morning, short at noon, gone at night. But I'll be back soon.
A hole leading in, a hole leading out, we connect to a cavern that is slimy all throughout. What are we?
A horrid monster hides from the day, with many legs and many eyes. With silver chains it catches prey. And eats it all before it dies. Yet in every cottage does it stay. And every castle beneath the sky.
Inside a great blue castle lives a shy young maid. She blushes in the morning and comes not out at night.
Power enough to smash ships and crush roofs. Yet it still must fear the sun.
You use it between your head and your toes, the more it works the thinner it grows.