Foraminifera

Foraminifera (/fəˌræməˈnɪfərə/, Latin meaning hole bearers, informally called "forams") are members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm that among other things is used for catching food, and commonly by an external shell or "test" made of various materials and constructed in diverse forms. All but perhaps a very few are aquatic and most are marine, the majority of which live on or within the seafloor sediment (i.e., are benthic) while a smaller variety are floaters in the water column at various depths (i.e., are planktonic). A few are known from freshwater or brackish conditions and some soil species have been identified through molecular analysis of small subunit ribosomal DNA.

Foraminifera typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in structure. These shells are commonly made of calcium carbonate (CaCO
3) or agglutinated sediment particles. Over 10,000 species are recognized, both living (8,708) and fossil (1,837). They are usually less than 1 mm in size, but some are much larger, the largest species reaching up to 20 cm.