foram

Foraminifera, commonly called forams, are single-celled protists distinguished by a hard shell, or test, that encases the cell. Most tests are calcareous or agglutinated and consist of multiple chambers added as the organism grows. The walls usually contain pores that accommodate cytoplasmic extensions known as reticulopodia.

Reticulopodia form a net-like feeding and locomotor system, used to capture suspended prey, trap detritus, and explore the surrounding water or sediment. Forams inhabit a wide range of marine and some freshwater environments, from shallow shelves to the deep sea, and may be planktonic or benthic.

Fossil foraminifera have a long record in marine sediments and are abundant in many rocks from the Paleozoic to the present. Because their tests fossilize readily and species appear and disappear in well-defined ways, forams provide valuable biostratigraphic markers for dating rocks and reconstructing past environments.

Isotopic composition and trace element ratios in calcitic tests yield information on ancient temperatures, seawater chemistry, and global ice volume. Collectively, forams contribute to paleoclimatology, paleoceanography, and petroleum geology, where they serve as indicators of reservoir quality and depositional history.

Taxonomically, forams are placed within the phylum Foraminifera and include a wide range of forms, from planktonic species that float in the water column to benthic species that inhabit sediments. They remain a central component of marine microfossil assemblages and a focus of ongoing research.