Stratonimbus

The stratonimbus replaced its ancestor the Nimbus. With the evolution of the more successful cloud nimbus, nimbus was pushed to edge of the Troposphere.There its adapted to survived with higher radiation and less water vapor until it was able to survive in the Stratosphere for a limited amount of time. There it was safe from the filter feeders. However there was no water vapor there so it would have to lower itself in the troposphere for water.

During the day it will rise up into Stratosphere where the sunlight is more intense and then during the night will come back down into the Troposphere where its warmer and can absorb water vapor.It has developed twice as many feathery fronds to help lift it into the air even when its thin. Like its ancestor it is transparent and absorbs ultraviolet light for photosynthesis. It can last for a long time without water or even air. When it comes in contact with moist air such as clouds it will begin reproducing. Those that get blown higher than the Stratosphere can stay dormant until they reach a more suitable elevation. Those that fall to the ground usually die and/or are eaten by other microbes.