Diatoms - Coscinodiscus
Coscionodiscus is one of the largest marine diatom genera. Coscinodiscus is a centric diatom. The image shows two cells. One cell is seen from the rectangular view (to the left) and the other from the top (or bottom) view (to the right). The rectangular view shows a cell lesser than that seen from the scales. The cell is brown and filled up with cell material covering the fine structures in the valves (cell wall) which is necessary to identify the specie.
Diameter about 400 my (1 my=1/1000 mm).