Groups of amoeba

After the children were born we lived in the suburbs. I found housekeeping and this type of life like the inside of a convent, only without coming in contact with anyone. In suburbs there are cliques. These groups of amoeba are interested only in their own swimming, and try to strike on to anything bigger than themselves and then try to grow and climb. Each group is oblivious to the ordinary surroundings. One could move to a suburb, establish a residence, exist and decay without the knowledge of anyone but the coroner.---by Salter

Hello,

What does "amoeba" refer to? I know the literal meaning--a creature.

Thanks!