Answer:
What travels from house to house and is sometimes narrow and sometimes wide but always stays outside?
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.
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
If you drop me I'm sure to crack. But give me a smile and I'll always smile back.
People take me on walks and I run and have fun. What am I?