 The foraminifera are a group of planktonic and benthic protists. That means they are single-celled organisms that float in the surface of the oceans or sit on the bottom of the oceans and live there. Foraminifera make their shells out of the mineral calcite, CaCO3. Planktonic foraminifera have a shell that's adapted to be buoyant in the water, whereas benthic foraminifera have a shell that's adapted to either rest on the bottom of the ocean or borrow in the sediment. This photograph shows a planktonic foraminifera which has a chambered shell. Individual chambers are formed and they rotate with the outermost chamber being the chamber in which the organism inhabits. The foraminifera extends protoplasm from its outermost chamber and this protoplasm is used to grab its prey, specifically other protists, including the caucolithophorids, diatoms, and dinoflagellates. At the same time, the protoplasm actually holds zooxanthellae, which are dinoflagellates that live in a symbiotic relationship with the planktonic foraminifera. The dinoflagellates help in the calcification of the foraminifera shell. Benthic foraminifera live on the bottom of the ocean and they have a very strong application in providing depth information about the ancient sediments in which they're living. They also tell us about the oxygen supply on the bottom and the amount of food that's delivered through the water column. Planktonic foraminifera are most widely used in reconstructing paleo temperatures. Their shells also tell us a lot about geologic time as the shell morphology has evolved through the course of geological history.