From fossils of thecamoebians, scientists know that Uttarkashi and Kedarnath areas in Uttaranchal were once covered by glacial lakes. This group of Thecamoebians are predominantly found in arctic ice cores. They are known to survive the freezing temperatures of the arctic. GSI Geologists recovered them at altitudes ranging between 1200 and 1400 meters. The fossils are approximately 6000 years old says a report of the GSI. In other words plenty of glacial lakes with ground moss existed in the area during that period. The study is being used to work out the downward limit of the coldest altitudes in the last 10,000 years. To survive the vagaries of their environment, thecamoebians change their body shapes. This trait has made them excellent indicators of chemical pollution within lakes affected by mining pollution, etc.