Winfrenatia is the oldest known terrestrial lichen,[1] known from the lower Devonian Rhynie Chert.
It comprises comprises a thallus, made of layered, aseptate hyphae, with a number of depressions on its top surface. Each depression contains a net of hyphae holding a sheathed cyanobacterium. The fungus appears to be related to the Zygomycetes, and the photobiont resembles the coccoid Gloeocapsa and Chroococcidiopsis.[2] There may be two separate algae, making the lichen a symbiosis of three organisms.[1]