I think it's so your lungs can expand to help you breathe properly ? You may have to wait for some more answers to come through
        
                    
             
        
        
        
Answer:
 Archaea 
Explanation:
Most extremophiles are microorganisms (and a high proportion of these are archaea), but this group also includes eukaryotes such as protists (e.g., algae, fungi and protozoa) and multicellular organisms. Archaea is the main group to thrive in extreme environments.
 
        
             
        
        
        
Ground my dude! wanna know how I know! I checked the other answers on the other one :)
        
                    
             
        
        
        
Explanation:
Cell groups that have the same function.