What is "archaeolithophyllum"

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

As of today, Archaeolithophyllum'' ''is the only Palaeozoic coralline to bear clear conceptacles, although the earlier Graticula does bear reproductive structures.

It mineralized using aragonite. Its conceptacles are cone-shaped protrusions that extend outwards from the thallus surface and have a single central opening. It probably encrusted muddy or sandy surfaces.