You mean they know what they’re eating?
A recent issue of a trendy organic living magazine had an article extolling the virtues of various women farmers, including a woman who runs a shellfish farm she inherited from her grandparents. The article notes that “[b]ecause shellfish naturally purify and filter water, they are a good example of farmed seafood that’s truly beneficial to the environment.”
I think I’ve just figured out how to make money out of my used Brita filters.