I walk on legs yet smaller than sand, I live through fire, the sea, and the land, In endless sleep, survival is planned. What am I?

Yellow, red, or black, In your mouth I leave no slack. One hard core I sometimes share, But juicy flavor always lingers there.

I sleep in winter or children's arms, I can be found in the stars, the snow, the mountains, and more, I am famously protective of my children

I am barrier, I am balance I am bound for life, I am shed away I am kin to the coldest of blood

Fish and fishermen love to have it, mastering it is a common habit.