As was shown by electron microscopy, the BM1 cells at different stages of life cycle were spherical and 18–59 μm in diameter (Figure 3b). Green flagellated and palmelloid cells possessed a thick (0.64–0.8 μm) extracellular matrix, which was thinner in the palmelloid and ―red‖ cells. All kinds of palmelloid cells formed (up to 0.4 μm) the thick cell wall. The chloroplast contained two to ten pyrenoids and a few starch grains (Figure 3a,d). In the resting ―red‖ cells, a pronounced decrease in the thylakoid volume and number was recorded; large merging lipid droplets were also present, which (Figure 3c) eventually occupied almost the entire cell volume.