Compsopogon

Compsopogon caeruleus is a species of red algae that lives in fresh water. It is the only species in the genus "Compsopogon" and the only representative of the family Compsopogonaceae. It is found in North America, South America, Europe, Africa, Asia, Australasia and Oceania. "Compsopogon" can tolerate a wide range of conditions in freshwater streams and occasionally in brackish lagoons and estuaries. It propagates by asexual spores.
"Compsopogon" presents a thallus of simple cylindrical cells inside large covered cortical cells. In more mature and large thallus interior cells can be disintegrated, leaving only the outer cortex.
The species exhibits a wide phenotypic plasticity in studies such as field observations, with the result that historically many species have been described, when current thought treats it as a single species. There are two main morphologies in "Compsopogon", one displaying regular cortical cells (morphology "caeruleus"), the other having cells with extra rhizoidals (morphology "leptoclados").