 The adult, or mature ascoceroid conch, as it is referred to, typically consists of an expanded exogastric brevicone with unique features.The apical end is formed by the septum of truncation which is about three times as thick as normal internal septa and about as thick as the external shell itself.The septa become confined to the dorsal side of the shell resulting in a series of dorsal chambers, or camerae, that provided stabilizing buoyancy.