This is Lithipodius nulla, a simple creature with a tendency, like any other species, to reproduce offspring. Lots of offspring.
Although the offspring inherit many characteristics of their parents,
no two individuals in the population are exactly the same.
This variation is vital to the survival of the species,
as only a fraction of the lithopodias will actually survive long enough to reproduce themselves. 
As a result, only those with characteristics that are best suited for survival in the environment
will pass on these successful traits to the next generation.
Those with characteristics less suited for the environment are less likely to survive and reproduce. 
This process is called natural selection, and over time and generations
it leads to the build-up of favorable characteristics in the population of a species. 
The result is a transformation of a population over time to suit its environment. This is known as adaptation.
Environmental pressures can also change, but as long as variation in a population exists,
new adaptations can occur, ensuring the survival of the species. 
