Cells are spherical or slightly ovate, uninucleate (with one nucleus) and a single parietal chloroplast without any pyrenoids.

The cell wall is covered in an irregular network of ridges, only visible in (scanning electron microscopy).

[2] Additionally, the genus itself is difficult to distinguish from other single small-celled genera such as Choricystis, Meyerella and Nannochloris; therefore, molecular data appear to be the only reliable way to identify species of Mychonastes.

Among species in the order Sphaeropleales that have been sequenced, it has the most compact, with a nuclear genome of 24.23 kB.

Mychonastes appears to be adapted for rapidly changing freshwater environments such as varying light conditions, nutrient concentrations, and temperatures.