This is a dinoflagellate, Ceratium, the anchor dinoflagellate. It is just possible to detect the wafting movement of the two flagellae when you watch these plant protists under high magnification. Ceratium needs serious magnification and careful lighting to display them in this way, and to catch the full beauty of their design and structural colour.
Bermuda (1978)
Nikon F2 | Custom Optics | Kodachrome 64