Acanthosphaera is a genus of green algae, in the family Chlorellaceae.

The cell is spherical, about 8–15 μm in diameter and uniformly covered in 20–40 spines.

The spines are distinctly thickened at the base, and very narrow at the tips.

[1][3] Asexual reproduction occurs by the formation of two, four or eight zoospores, released via the rupture of the parental cell wall.

[1] The original author Korshikov described the presence of 4-flagellate zoospores, but this has not been confirmed in subsequent reports.