See text Tetraedron is a genus of green algae in the family Hydrodictyaceae.

[1] Tetraedron consists of single, free-floating cells, making them phytoplankton.

They are flattened, triangular, quadrangular, or irregularly polygonal in shape; old cells are nearly spherical.

Among the green algae, the genus Chlorotetraedron appears similar, but differs from Tetraedron in its ability to produce zoospores.

Segregate genera include Pseudostaurastrum, Goniochloris, Isthmochloron, Tetraedriella, Tetraplektron, and others.