Answer:
Alive without breath, As cold as death, Clad in mail never clinking, Never thirsty, ever drinking
I can be moved. I can be rolled. But nothing will I hold. I'm red and I'm blue, and I can be other colors too. Having no head, though similar in shape. I have no eyes - yet move all over the place.
Long and slinky like a trout, never sings till it's guts come out.
They're up near the sky, on something very tall. Sometimes they die, only then do they fall.
What goes in, but never through? I've got some and so do you. We might lend one, or even two, but only if our trust is true.
I am a cave full of bones and the house of a worm.