1 billion is a newcomer. Diskagma buttonii fossils from S. Africa are dated to ca. 2.2 billion years old.
Were they marine life, or terrestrial?
"Loron said the finding was significant because in the tree of life, fungi are part of the same umbrella group of organisms - known as Eukaryotes - as plants and animals. This means that if fungi are already present around 900-1000 million years ago, so should animals have been,
about the Diskagma buttonii - no one is sure what they were,
"They most resemble modern soil organisms called Geosiphon, a fungus with a central cavity filled with symbiotic cyanobacteria."
They may have had something to do with the rise of Oxygen in the atmosphere
This gains added significance because fossil soils hosting the fossils have long been taken as evidence for a marked rise in the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago, widely called the Great Oxidation Event.
Newly named fossil Diskagma is comparable in morphology and size to Thucomyces lichenoides, a fossil dating to 2.8 billion years ago and also found in South Africa, but its composition, including interior structure and trace elements, is significantly different.
The new fossil is a promising candidate for the oldest known eukaryote - an organism with cells that contain complex structures, including a nucleus, within membranes,
most of the rock from that period and earlier has long been subducted into the Earth. What they are finding might be said to be like looking at a farmers field and deducing the state of our present civilization: most of the evidence for what may have existed then is gone now and we are left with guesses based on little evidence and many assumptions (all of which could well prove to be wrong).