Diatoms are circular or oblong shaped. They are single-celled, and float helplessly in the water or attach themselves with a jellylike substance to stones or other water plants. Diatoms reproduce by cell division. Under some conditions, they can make their own food. They produce their own organic nutrients from the environment, and store food in fatty deposits inside the cell.
Diatoms are single-celled algae that add silica to their cell walls for strength.
Their shells are very complex and are occasionally used in polishes and toothpaste, as a binder. There are about 70 species of dinoflagellates around the continent of Antarctica. Dinoflagellates are a single-celled algae with a nucleus. They are round and are mostly the same as the diatoms except that they produce nasty toxins. Red tides are very dangerous because they can kill an animal that ingests the substance.