Testosterone is the principal male sex hormone.
        
             
        
        
        
The Marcellus Shale also categorized as the Marcellus formation is a marine sedimentary rock unit of middle Devonian age found in eastern North America. It elongates throughout the major of the Appalachian Basin.  
The shale comprises huge unexploited reserves of natural gas, which makes it an attractive target for export and energy development. There are comparatively scarce presences of fossilized marine fauna found in the Marcellus, however, these fossils are still essential to paleontology.  
For example, the Marcellus comprises the primogenital known varied assemblage of thin-shelled mollusks, still possessing well-preserved shell microcomposition. It is also where goniatite, an extinct shelled swimmer identical to a squid, make their initial presence in the fossil record.  
 
        
             
        
        
        
It is a process that causes rock to break into little pieces.
        
                    
             
        
        
        
Darwin's idea of the survival of the fittest means that certain organisms are more likely to survive with they traits in particular environments. This is because some organisms are more fit to live in a given environment whether it be due to temperature, weather, or predators.
One example is that dark moths are more fit for survival than light moths in many areas because they are able to camouflage against dark tree bark.
Hope this helps.