Answer:
Where humans breathe liquid.
They can be long or short; they can be grown or bought; they can be painted or left bare; they can be round or square.
What freezes after it is heated up?
What body part is pronounced as one letter but written with three, only two different letters are used?
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?