Oyster Shells?

Hello All - I had what is no doubt one of the oddest, but at the same time intriguing, questions ever asked me by a contractor today. Her question: Can the mother-of-pearl / oyster shells components in a terrazzo floor be considered or counted toward the rapidly renewable credit? We're researching the typical life cycle of an oyster, but provided we can find a set of strong parameters--i.e., farmed vs. wild--what do you think? Do formerly live molluscs qualify? Any and all witty responses welcomed.