Deep-sea, fine-grained, pelagic deposit containing more than 30% calcium carbonate. The calcium carbonate is derived from the skeletal material of various planktonic animals and plants, e.g. foraminiferan tests and coccoliths (which are calcitic), and pteropod tests (which are aragonitic). Calcareous ooze is the most extensive deposit on the ocean floor but is restricted to water depths less than about 3500 m. See also carbonate compensation depth.