I have never heard of a growth with an eye...but I have heard of cartlidge, teeth, and hair, growing on a mass...in ab. cavity they are called (I am writing this phonetically) a numoid. They are a benign, auto growth.
From the nasty Discovery (or whatever) story, "soft" growths (like eyes) are generally not discovered, whereas hard growths (like teeth or whatever) are more prone to cause trouble or be discovered on X-rays.
The theory was that they occur with equal frequency, however, as there was no reason for them not to do so.