In several parts of the world, such as the seas off the coast of Florida, toxic dinoflagellates sometimes develop into enormous blooms called red tides.

ECONOMIST: What killed Fossil Lake?

The algae, known as Symbiodinium, is part of a group of creatures known as dinoflagellates, which are responsible for processing one-third of all CO2 in the world's oceans, reports Science Daily.

CNN: All About: Coral Reefs

Many dinoflagellates are harmless, but some produce neurotoxins.

ECONOMIST: What killed Fossil Lake?