Mother of pearl is actually a natural shell material, though like pearls it is made up of the layers inside of shells called nacre. It comes from the various types of sea shell mollusks such as oyster shells. If you have ever opened an oyster shell and looked at the inside of it, you may have noticed how it has a luster to it, sort of a shiny affect. This is what can eventually turn into a pearl, but before it does that, you have a thin material that lines the inside of these mollusks shells.