Calcareous ooze is the general term for layers of muddy, calcium carbonate (CaCO₃) bearing soft rock sediment on the seafloor. Of all the distinct types of veneers covering the Earth's crust—be it soil, sediment, snow, or ice—none are more widespread than red-clay and calcareous ooze. Only a small proportion of calcareous ooze is precipitated inorganically. For the most part, calcareous ooze comprises the fossil hard parts of planktic (Greek planktos = floating around) and benthic (Greek benthos = the deep) single-celled marine organisms whose calcium carbonate skeletons are discarded upon death or reproduction. Calcareous ooze is distinguished by its main biogenic component into foraminiferal ooze, coccolithophore ooze, or pteropod ooze, respectively. However, coccolithophorids and planktic foraminifera form the largest part of the pelagic calcareous ooze with less contribution due to pteropods, calcareous dinoflagellates, and lithothamnium.

Foraminiferal ooze contains foraminifera (in Latin, foramen = hole; ferre = bearing), large...