Marblehead fish?

Question

Have you ever heard of a fish that has a marble type thing in it's head? The marble supposedly has either an L or R on it. If you've heard of it, what is the real name of this fish?

Answer 1

Walleyes are often referred to as "marble eyes" due to the appearance of the pupil of their eyes, which have a milky look. Never heard of anything else even close.