Well, oysters draw all of their flavor from their environment; they literally breathe and eat water at a rate of 50 gallons a day. Obviously, whatever is in that water is going to affect the taste of the oyster. I think of them as little lenses that concentrate everything going on in their bay or estuary and pack it into a morsel of flesh. Also, oysters_ _aren't typically manipulated much by chefs and producers; by and large, we eat them in a raw, unmediated state. That's why I'd say that oysters actually express terroir even better than most wines, since in the case of wine, while the grapes may get some of their flavor from the soil, the winemaking process introduces many other variables, like yeast and fermentation and cellaring conditions.