Fresh clam chowder may contain a small amount of sand due to clams being filter feeders, which can lead to grains of sand remaining in the meat. While canned versions often have sand, fresh clams can be purged of sand by keeping them alive in salted water and feeding them corn muffin mix for a couple of days, allowing them to expel the sand. This technique, however, is not applicable to other types of shellfish, such as "prairie oysters." Overall, the presence of sand in clam chowder is a common expectation, especially with fresh clams.