A septum (Latin for something that encloses; plural Septa)'s a partition separating two cavities or spaces. Examples include: Nasal septum: the cartilage wall separating the nostrils of the human nose. Cephalopod Septa: walls between each chamber, or siphuncle, in shells of nautiloids, ammonites, and belemnites; for example cephalopods that retain an external shell. The wall dividing the right side of the heart from the left side. A partition dividing filamentous hyphae into discrete cells… (More on Septum)