What is a Foram?
Forams are single-celled organisms that typically live in the ocean and produce a mineralized test (shell). Foram tests are generally composed of secreted calcium carbonate (CaCO3), but less commonly they may be composed of organic material or cemented particles scavenged from the sea floor.
Forams produce tests in a range of shapes and sizes. Some tests are simple, single-chambered forms like the one shown in the photo below, while others are multi-chambered and elaborately structured. Typically they are microscopic in size, and generally range from 0.1 to 1 mm. (approximately the size of a grain of sand or smaller). However, in the geologic past, forams with test diameters greater than 10 cm. (4 in.) were not unusual.