Foraminifera are amoeba-like, single-celled protists (very simple micro-organisms). They have been called 'armored amoebae' because they secrete a tiny shell (test) usually between about a half and one millimeter long. They get their name from the foramen, an opening or tube that interconnects all the chambers of the test. Fossilized tests are found in sediments as old as the earliest Cambrian (about 545 million years ago) and foraminifera can still be found in abundance today, living in marine and brackish waters. Although each foram is just a single cell, they build complex shells around themselves from minerals in the seawater. These shells have accumulated in layers of sediment below the seafloor of the open ocean and in regions where the ocean once flooded the continents for millions of years. By examining the shell chemistry of these ancient forams, scientists can learn about Earth's climate long before humans ever walked the planet and get insight into how climate changed in the past.
Sources: Smithsonian National Museum of Natural History, NERC Science of the Environment
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