Cocconeis

Use in primary schools, secondary schools and universities. The model shows a siliceous cell wall of microscopic unicellular algae - diatoms.  These are two pennate diatoms, abundant in fresh waters, Navicula and Cocconeis. The basic structures of the shell (frustule) correspond to reality. The frustule consists of two parts that fit together like the lid and bottom of a box (separable, it is possible to add chloroplasts, nucleus, ...). Navicula has a raphe (slit) on each half of the frustule (Cocconeis only on one), and both diatoms have striae (pores in a line on the surface).
Use in primary school: unicellular organisms, unicellular algae most widespread in fresh waters, it is possible to add chloroplasts, nucleus, etc., photosynthesis, movement, in the geological past of the Earth - formation of diatomaceous earth (filtration of beer, wine, building material, insulating material, dynamite, toothpaste), formation of oil (southern deposits) - from organic matter of diatoms.
Use at secondary school, university: unicellular algae, pennate diatoms, construction of diatom frustule, from two parts (epitheca, hypotheca), raphe, striae, pores, movement of diatoms, determination of two representatives: Navicula, Cocconeis. Photosynthesis, function in the ecosystem, human use.