E. huecoense E. johnsonii (type) E. magnum Eugonophyllum is a genus of green algae in the family Halimedaceae.

[1] The alga is phylloid, meaning it has leaflike photosynthesizing structures called thalli (singular: thallus).

The thicker inner cortex consists of anastomosing utricles; that is, small sacklike structures joined by openings to their neighbors.

[1] The alga is calcareous and its remains are important components of carbonate rock beds of Pennsylvanian to early Permian.

[3] It is particularly prominent as a carbonate producer (together with Paraepimastopora kansasensis) in rocks of Kasimovian to Gzhelian age, in regions of warm water notably close to glaciated continental areas.