Cryptomonas is the name-giving genus of the cryptomonads. It is common in freshwater habitats and often forms blooms in greater depths of lakes or during winter time underneath the ice. The cells are usually brownish in colour and have an invagination with a slit-like opening - called a furrow-gullet system - lined with several rows of ejectosomes (also ejectisomes: explosive organells). They are not known to produce any toxins and are used to feed small zooplankton, which is the food source for small fish in fish farming.