When paired, the two cells are joined at the base by spines or leaf-like appendages that twist together.

The cell wall is smooth and covered with thin spines up to 24 μm long.

[2][1] Reproduction occurs asexually via the formation of autospores or zoospores which form a coenobium while still in the mother cell wall.

In their 1983 monograph, Jiří Komárek and Bohuslav Fott placed Paradoxia in the family Characiaceae.

[3] A strain labeled as Paradoxia multiseta in the UTEX-Austin culture collection was found to have a close phylogenetic relationship to Coccomyxa; however, the morphology of the strain (having spherical cells) does not appear to match that of Paradoxia, making the identity suspect.