I read the same from both sides, I'm calm, even, and used to measure how flat things are

Columbus travelled the seas with me, Harry's parents filled his vault with me. Lose one letter and you can measure fluids with me.

With a twisted spine I clear the neck Keep it straight and in line Now enjoy some fine wine

In summer's warmth, I stand tall, a rainbow on a stick. My icy embrace melts with time, leaving sticky trails of sweet joy.

Brown and dead, A body with no head. Found in water and not buried underground, Floating away and not sinking down.