Foraminifera

Foraminifera are single-celled protists characterised by streaming granular ectoplasm used to catch food, and commonly by an external shell called a test built from diverse materials. Most foraminifera are marine, with the majority living on or within seafloor sediment while a smaller number float in the water column at various depths, belonging to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and a small number of nonaquatic soil species have been identified through molecular analysis of ribosomal DNA.