What am I?

A flash of light on a grey day. If you're made of metal, you best stay away. What am I?

related riddles

I wear a red coat and have a stone in my throat. What am I?

When you take away the whole from me, there is always some left. What am I?

In a tree you'll find me moving slow as can be. My name is a sin but from them I am free. What am I?