Cell-sized Thermometers

Some benthic foraminifera, such as the one shown in this scanning electron micrograph, are single-celled organisms whose calcium carbonate shells contain information about the temperature of the water they grew in. This may allow scientists to use them as proxies for past deep ocean temperature. This specimen, Bulimina sp., measures about 400 x 250 micrometers (0.02 x 0.01 inches.) (Photo by Joan Bernhard, Woods Hole Oceanographic Institution)