Archaeolithophyllum is a genus of conceptacle-bearing red alga that falls in the coralline stem group.

[1][2] As of today, Archaeolithophyllum is the only Palaeozoic coralline to bear clear conceptacles,[3] although the earlier Graticula does bear reproductive structures.

[3] Its conceptacles are cone-shaped protrusions that extend outwards from the thallus surface and have a single central opening.

[5] It probably encrusted muddy or sandy surfaces.

This Rhodophyta-related article is a stub.