(Müller, 1856)
Spicules sharp at both ends, proximally cylindrical, distally conical. At 1/3 length finely perforate rhomboid plates form; plates fusing together tightly, forming thin-walled spherical or ellipsoidal shell. Diameter of latticed shell: 0.20 by 0.22 mm; cell body: 0.18 mm; spicule length: 0.24-0.26 mm.