Imagine you own a plot of land under which oil is found. Whether or not you have a right to a share of the wealth is determined by whether you own the mineral rights. Suppose you own a field and one day you discover a previous owner buried their life savings on the property 160 years ago. This year the owner of a cornfield in Kentucky found more than 700 gold coins dated between 1840 and 1863 buried on his land. Does he own those coins? Generally, unless there was some compelling evidence that the original owner was the government or it was used in a crime.
How about if your doctor was treating you for cancer and discovered an interesting phenomenon in your cancer cells?