Haeckel
Diagnosis: Spherical shell with hemispherical valves. Galea arched, with large nasal opening. Four primary tubes bifurcate at right angles 4 to 6 times. Branches smooth and straight, or slightly curved. Ends of terminal branches sometimes with very small inflated disc with 4-7 (usually 4) short recurved teeth.
Diameter: 0.55-1.8 mm.