As the bacteria consume the nutrients, they begin to grow and multiply. This generates thousands to millions to billions of cells that begin to pile up, becoming visible to the naked eye. This pile of cells originates from one cell and is called a bacterial colony. Each species of bacteria produces a colony that looks different from the colonies produced by other species of bacteria. Examination of the form and structure of bacterial colonies is termed colony morphology and is one of the first steps in characterizing and identifying a bacterial culture.