Water Wool

Water wool, accumulation of freely floating filamentous green algae, primarily Spirogyra, Mougeotia, Zyg-nema, widely distributed in stagnant freshwater waters. During the day, during the process of assimilation of CO₂, W. w. mostly floats on the surface of the water and bubbles from the released O₂, but at night and in cloudy weather it sinks to the depth. In such W. w., many small animals often accumulate, which find here an oxygen-rich environment, feed on the algae and have shelter from larger animals. Upon dying, W. w. gives rise to silt, sometimes having therapeutic value. Thus, for example, in the main mass, is the origin of the silt of Tambukan Lake near Pyatigorsk.