Unicellular desmid with two rounded semicells separated by an isthmus or constriction. The semi-cells may have a somewhat triangular or trapezoidal outline with a bumpy surface. Each semicell contains a green chloroplast with pyrenoids.
Cosmarium, X400. Photo: Phil Novis, Manaaki WhenuaCosmarium, Lake Dunstan, X640. Photo: Otago Regional Council & Manaaki Whenua
Typical habitats
Common in wetlands and other slow-flowing shallow habitats
![[Cosmarium], X400. Photo: Phil Novis, Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/cosmarium_phil400__ScaleWidthWzEwMjRd.jpg)
![[Cosmarium], Lake Dunstan, X640. Photo: Otago Regional Council & Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/cosmarium640__ScaleWidthWzEwMjRd.jpg)