The members of this family are found in muddy sand or gravel at or below low tide mark. They have characteristically rounded shells with forward-facing projections. The valves are flattened and etched with concentric rings. Each valve bears two cardinals and two plate-like lateral teeth. These molluscs do not have siphons but the extremely long foot makes a channel, which is then lined with slime and serves, for the intake and expulsion of water.