Dinoflagellates (dinos) are single-celled marine plankton (algae). More specifically, our dinos are a species of non-toxic phytoplankton known as Pyrocystis fusiformis. During the day, they photosynthesize just like plants do. At night, these dinos have the ability to bioluminesce in response to movement.
Fin fact- dinos produce more than half of the Earth's oxygen. That's more than all the grass, trees, forests and rainforests put together!