The family is monogeneric, and the genus is monospecific. Test external, spirally coiled. See below.
Spirula Lamarck, 1799:
« Shell partially or completely in a spiral, and from which at least the last whorl is separated; chambers transverse, simple, the disc of which is pierced by a tube. » – J. B. M. de Lamarck: “Prodrome d’une nouvelle classification des coquilles”, Mémoires de la Société d’Histoire Naturelle de Paris vol.I, Paris 1799, p.80.
