k_spiridoula's Identifications

They have two perpendicular flagella. They also have a cellulose plate which is their armor. It is seen to have a greenish coloration.
Most of them are marine, but some live in freshwater. These dinoflagellates were found in the water from Castor Beach. They are the main cause for red tides. They even produce toxins, some of which are the most poisonous known.
https://www.britannica.com/science/dinoflagellate