We visited two late Cretaceous sites in Montgomery County, Alabama, where we collected primarily shark teeth and echinoids. A surprise awaited - one site we have visited for years used to have a huge sand pile shaped like a mushroom that was filled with shark teeth. The mushroom is no more, and all that is left is a sandpile. Last we heard, the sand was being used in the zoo. You don't want to know any more than that!
(Photos courtesy Brian Ward.)