This was considered The Examiner-1, however we ruled this possibility out due to the fact that it would have involved at least 4 different birds carrying the seashells over 200 miles inland on 4 scattered dates, which is highly unlikely.
Hmm, who says it was from an ocean? In the midwest we have small fresh water clam shells in lakes and ponds. I think the bird theory and storm could be more possible if it came from somewhere closer, like a near by lake or pound.
Both of these ideas are very possible MizBejabbers. My co-workers and myself couldn't solve this mystery on our own, which is why I decided to raise this question to all of my friends here at the Hub Pages.