Diatoms - Asterionella and Fragilaria
The two genus Asterionella and Fragilaria occur often together in water rich of nutrients. They are diatoms with symmetry about a line and so look oblong seen from all points of view.
Asterionella, characteristic small stars, is one of the commonest plankton-algae.
The cell length to Asterionella formosa is 40-80my
Fragilaria have cells joined centrally to form colonies like double-sided combs. Fragilaria crotonensis is an indicator of polluted water.
The cell length to Fragilaria crotonensis 40-170my.