Genus Sphaerastrum Greeff, 1875, emend. Mikrjukov, 1996

 

Diagnosis: Centrohelid heliozoa with the cell body covered by a mucous coat and a thick jacket of mainly tangential organic spicules. Siliceous elements in the cell envelope are absent.
One species: S. fockii (Archer, 1869), emend. Mikrjukov, 1996