O.K., ... they aren't exactly rocks.
Our friend Stefano at Hotel Posa Posa told us at breakfast how people in Positano toss their old tiles out into the sea and that they wash up on the beach, time worn, something akin to sea glass. He told us that he chips off the part of the tile without the color and uses the colored pieces to make mosaics. Cool, right? He was asking guests to each bring back one of these "rocks" from the beach for another project. One?
Well, I love a project. (And if has something to do with hunting for things on the beach, all the better!) My Mom and Dad were in on it as well and in the process we found a funky little place with fabulous seafood linguine. The restaurant is basically built on a rock, as you can see in the bottom photo. As you can also see, we got a little carried away with the hunt.

Could it be ... ?
Mom and I sorting just a few of at lunch ...
The waitress laughed, "Positano Rocks!" and used them as a trivet!
Under the restaurant ... if you click to enlarge you can see a little blue tile in the foreground ...
This gives you a better idea of the location of the restaurant!

My mom got so excited by the tiles she thought about making her own mosaic table but my Dad, standing there with his backpack loaded down with tile, reminded her of the hand-painted tiles that were already in her suitcase from Assisi and the other very heavy tiles on hold at the ceramics place in town. So, Mom and I picked out of few tiny ones to bring home as keepsakes and that evening handed Stefano a bag full of "Positano Rocks."
I uploaded these photos and wrote this post yesterday, not realizing after running out of time, that it would post on September 11th. I so hope we can all find peace and healing for the trauma of that day and all that has happened since.
Your daily life is your temple and your religion.
... And if you would know God
be not therefore a solver of riddles.
Rather look about you and you shall see Him
walking in the cloud, outstretching His arms
in the lightening and descending in rain.
You shall see Him smiling in flowers,
then rising and waving His hands in trees.
~Kahlil Gibran
from The Prophet