Glassclams

A species of clam rarely found in most of the world, but regularly found in the waters around Konos.
Glassclams are incredibly hard to find for most people, given that they blend in almost perfectly with their surroundings due to the mimicking abilities of it's outer shell. The glass like texture of it's shell is able to present images on any side of the creature, as if the clam was perfectly clear all the way through. 
They're sought after creatures for their size, making them feasible to cultivate for their meat (though all attempts to do so have failed in relatively short order), but more traditionally for the large pearls that they produce. Many of them making great centerpieces for necklaces and diadems/circlets/crowns.