Diatoms
are unicellular algae (many are around one twentieth of millimeter
long). They possess plastids and the same cellular organelles as other eukaryotic photosynthetic algae.
The hallmark of a diatom is its cell wall named frustule. This wall, heavily
impregnated with silica, is highly differentiated. It consists always
of two large intrically sculptured units called valves, together with
several linking structures termed girdle elements. Each species is
characterized by a particular shape of the frustule and by the decoration of the valves.
After removal of the organic matter, i.e. of the cell, and cleaning of the siliceous wall of the collected diatoms,
coloured micrographs were taken. They allow to discover the beauty and
the diversity of the diatoms :