What am I?

I only have two backbones and thousands of ribs. What am I?

I have keys but no doors, I have space but no rooms, I allow you to enter but you are never able to leave. What am I?

I cannot hear or even see, But sense light and sounds there may be, Sometimes I end up on a hook, I can be combined with a book. What am I?

A container holding water but not a cup. If you want to find me, look up. What am I?

Riddles and Answers