Just to take that post from John on Oyster Shells a bit further, the proof is in the Black Oyster Shells. Oysters are not Black, Dark Blue or Gray. Oysters are an off white color and when bleached by the Sun they become white. Why are they Black? They are Fossils. Just as John said, Oysters do not really live in the Ocean, they are a "Calm" water specie and need certain Salinity and Chemicals to prosper. They are Black because they have been buried with no exposure to Oxygen, just like Fossilized Shark Teeth. As the Beach migrates to the West, the rough Surf has uncovered ancient Shellfish beds that were in the Sound thousands of years ago. These Black Oysters are all over the beach and not worth anything, but come with a good story. The book "How to Read a North Carolina Beach" has a whole chapter (either 6 or 7) on this. I know in my Volunteer work I'll ask children to hold a Black, well worn Oyster Shell, the conversation goes on to you are holding something 10,000 years old. The usual reaction is "Wow" and disbelief. Just sayin.