Forams have tests and live only in marine environments, and the largest may be seen by the naked eye. Tests are single-chambered or multi-chambered and are composed of organic materials; most are made of calcium carbonate, but some forams' tests are composed of echinoderm plates or sponge spicules. Forams are omnivorous, and some host symbionts, such as dinomastigots, chrysomonads, and diatoms. Forams reproduce sexually and asexually and alternate between diploid and haploid generations. .
Phylum Xenophyophora.
Members of phylum Zenophyophora were first identified as sponges and were later believed to be large marine rhizopods; both of these observations were incorrect. Xenophyophores are phagotrophes that feed on bacteria and other protists. Xenophyophores cannot be cultured and are usually damaged upon collection, so they are extremely difficult to study and very little is known about them. They are plasmodia, "multinucluate masses of cytoplasm," and have pseudopods. The tests of Xenophyophores, which may be hard, brittle, or flexible, are composed of various substances, such as foram tests, radiolarian skeletons, sponge spicules, and mineral grains. There forty-two species of xenophyophores; they are organized into five families and two classes.
Phylum Myxomycota.
The members of phylum Myxomycota are plasmodial slime molds which, unlike cellular slime molds, reproduce sexually; 400 or 500 species of myxomycotes are known. of the members of this phylum alternate between diploid and haploid generations. Plasmodia are slimy and wet in texture, and although they may have orange or yellow pigments, they do not photosynthesize; they are phagotrophic, and they feed on bacteria and small protists that are found on decaying vegetation. Plasmodia move by differential growth; under a microscope this movement is obviously "intraplasmodial flow." If their environment becomes drier, they may mature to "the fruiting stage," during which sporangia (spore-producing organs, also called sporocarps) form.