Foraminifera are organisms smaller than the tip of a sewing needle. They build a calcium carbonate shell during their lifetime. They live in the seafloor – benthic foraminifera – or “floating” near the ocean surface – planktic foraminifera. When they build their shells, forams use the chemical elements of the waters they live in. That is why their shell’s store information of the seawater at the time they lived. This makes foraminifera very useful to study.