Metanephridium (pl. metanephridia) is a type of excretory gland or nephridium found in many types of invertebrates such as annelids and mollusks. It typically consists of a ciliated funnel opening into the body cavity or coelom connected to a duct which may be variously glandularized, folded or expanded (vesiculate) and which typically opens to the organism's exterior. In many earthworms these nephridial ducts open into the digestive tract instead.
