Coccolithophore

Scanning electron micrograph of a coccolithophore. Coccolithophores are single cell marine plants found in the upper layers of the ocean. These phytoplankton surround themselves with plates or scales called coccoliths, which they make from calcium carbonate inside the cell and then secrete. The biological function of coccoliths remains uncertain but may play a role in affecting buoyancy and possibly also act as a defensive measure. Photosynthesis provides the main source of energy and carbon for the organism. They are approximately 5 micrometres in diameter.