Answer:
I have a head and a tail but my eyes can never see my tail.
I can be thin but not fat; in your body but never on your placemat. I'm always better when I'm fresh but you'll never see me in the flesh.
I am seen in the water. If seen in the sky I am in the rainbow a jay's feather and lapis lazuli.
What has banks but no money a bed but no sleep waves but no ocean?
What has 4 fingers and a thumb but isn't alive?
What made Cyclops quit teaching?