One-celled organisms are microscopic organisms that consist of only one cell. Examples of one-celled organisms include amebas (6 letters), amoebae (7 letters), BACTERIA (8 letters), amoebas (7 letters) and MONADS (6 letters). These organisms are typically found in aquatic environments, such as ponds, lakes, rivers and oceans. They are important for the health of the environment, as they are a major source of food for other organisms.