I dig out tiny caves, and store gold and silver in them.
I also build bridges of silver and make crowns of gold.
They are the smallest you could imagine.
Sooner or later everybody needs my help,
yet many people are afraid to let me help them.
Who am I?
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 ‘neath the sky.
What is it?