A "pearl" is a metaphor for something very rare, fine, admirable, and valuable. And yet, to the oyster, the pearl is nothing more than an irritation to be tolerated.
The pearl begins as a bit of wild stuff, sand, that enters the shell. The oyster then covers the sand with calcium carbonate. To us a bit of mucus. After time, a pearl is made.
We go through life looking for rare pearls. We value them because of their rarity, their symmetry, and their beauty. But, beauty is often to be seen and enjoyed, one just has to look. A book, for instance, may contain wonders that will open a mind. Just open the book and read. The same with the internet. Its beauty is in the endless possibilities that it presents, both as a source of education, and as a means of communication. But, like anything else you have to look for the possibilities and use it.
The azuelos (blue tiles) that decorate the facade and interior of the church are prized by the Portuguese as a common means of ornamentation on many buildings. But, the materials of the azuelos themselves, like the stone from which the building is constructed, is nothing more than a form of the calcium carbonate and sand that makes up a pearl.
So, the next time you pick up a little sand and clay, think about the possibilities. As endless, one might say, as the number of grains of sand in all the beaches of the world.