I am covered in hundreds of sharp needles all winter long, yet I cannot sew a single Christmas sweater. What am I?

If you throw a heavy blue stone into the deep red sea, what does it become?

What is a rib cage's favorite subject to debate in philosophy class?

What gets sharper the more you use it, yet stays in the exact same place?

I am a promise made to yourself that has a very short shelf life, usually broken before February rolls around. What am I?

If you drop me from the highest skyscraper, I will survive every time. But if you place me in the shallowest pool of water, I will die instantly. What am I?

I am a silent painter who decorates your windowpane with icy fern patterns overnight without using a brush, only to vanish when the sun warms the air. Who am I?