Tiny creatures can refer to two different organisms: amoebas and mites. Amoebas are single-celled organisms that move by extending and retracting their pseudopods, or false feet. They are found in freshwater and marine environments. Mites are arachnids, related to spiders and ticks, and are usually less than 1 millimeter in size. They are found in a variety of habitats, including soil, water, and plants.