Answer:
I have four legs but no tail. Usually I am heard only at night.
Covered in stone and sun. It's home to many but also none. What is it?
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
What goes further the slower it goes?
What is the heart of many risks, has a heart, but is not a living being?
I always murmur but never talk. Always run but never walk. I have a bed but never sleep, have a mouth but never speak. What am I?