Pond Life 
time, only the lowest and most minute 
forms are found. But we very soon 
learn that mere size is in itself nothing. 
All the elephants which have ever existed 
have done nothing to alter the face of 
the earth; they have trampled down 
trees and pulled up plants by the roots, 
lived and died, leaving the world exactly 
as they found it. But the lofty lime- 
stone and coral rocks and chalk cliffs 
have been slowly raised by countless 
millions of creatures, invisible to the 
naked eye, by the power they have of 
being able to take the lime and chalk 
from the water to make their shells with. 
These shells, long after the animals 
which once inhabited them have died, 
have slowly accumulated, and in the 
course of time have formed the hills and 
mountains which help to make the 
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