Genus: Free-living; skeleton with or without coat; spicules included in a coat more or less visible;
radial siliceous spicules; ordered spicules (Illustrated Guide, 1985).
Mucilaginous envelope with spindle-shaped or discoidal spicules which extend normally
outwards along pseudopodia (Kudo, 1966).
Sphaerastrum fockei Greeff,
cell body μm long, μm wide,
x 640, Naruto town, Chiba Pref., Japan, September 2003 by Y. Tsukii
50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640