Why are natural pearls so hard to find? It seems pretty sensible that there would be tons of natural pearls produced each year. Right? If pearls are formed by an irritant, bacteria or other organism invading the soft inner body of a mollusk, well, surely that happens all the time! At least that is what I think. But, here is the secret... pearls are not the only response that mollusks have to invasions by irritants, bacteria or other organism.
Mollusks are filter feeders meaning they are constantly syphoning water in and out of their bodies. Think of it as a constant flow in and out, in and out. So, if something gets IN that shouldn't be there, they want it OUT! So, step one is to try to slowly work the irritant out of the body.
The sad truth is if the mollusk cannot work the irritation out of its body, it might die. This is an unfortunate response to an invasion or irritant.
If the mollusk does live, it will start coating the irritant with the same mother-of-pearl material that it uses to make its shell. Here is the catch, though, once it produces a pearl, it will STILL try to remove the pearl from its body. So, many natural pearls are merely released by the mollusk, never to be discovered. So, just because some mollusks creates a pearl, that does not mean we will find them!