I believe the answer you're looking for is:
Condensation- If the air cools, then water vapor molecules slow down and some can not remain a vapor. They cluster in the air to form tiny liquid droplets. This is called condensation. In clouds, the liquid droplets formed by condensation are small and light enough that they stay in the air.
<em>hope this helps! :)</em>
Answer;
-Pellicle
Explanation;
-Protist cells may contain a single nucleus or many nuclei; they range in size from microscopic to thousands of meters in area. Protists may have animal-like cell membranes, plant-like cell walls, or may be covered by a pellicle.
-On a paramecium's exterior is found the pellicle. The pellicle is stiff to maintain the paramecium's shape and provide stability but it is also flexible to allow movement. It also acts as an attachment site for external organelles such as cilia.
