Phylum Foraminifera (d'Orbigny, 1826)
Foraminifera are typically deﬁned as unicellular organisms characterized by the presence of granuloreticulopodia. Some species are naked, but most have a membranous, agglutinated, or calcareous test, which is either monothalamous (single-chambered) or polythalamous (multi-chambered). Foraminifera live in marine and brackish water, but some members of this phylum can be found in fresh water, submerged mosses, sediments, and also in mosses growing on soil, trees and walls. These species seem to be rare, only a handful of people ever found one, despite of their relatively large size. All known freshwater and soil species are monothalamous, and therefore called monothalamids or traditionally ‘allogromiids’, and now defined as foraminifera that are either naked or possess a monothalamous test. This test can be smooth or covered with agglutinated particles gathered from the surrounding sediment. These three morphotypes are respectively called naked, organic-walled and agglutinated monothalamids, an artificial classification that has no phylogenetical base, because many monothalamid clades comprise both organic-walled and agglutinated species.
Usually the amoebae spread out their pseudopodial network when kept in petri dishes or on microscope slides in moist chambers.