https://www.pnas.org/content/early/2019/02/05/1815721116

The 2.1 billion-year-old sedimentary strata contain exquisitely preserved fossils that provide an ecologic snapshot of the biota inhabiting an oxygenated shallow-marine environment. Most striking are the pyritized string-shaped structures, which suggest that the producer have been a multicellular or syncytial organism able to migrate laterally and vertically to reach for food resources. A modern analogue is the aggregation of amoeboid cells into a migratory slug phase in modern cellular slime molds during time of food starvation. While it remains uncertain whether the amoeboidlike organisms represent a failed experiment or a prelude to subsequent evolutionary innovations, they add to the growing record of comparatively complex life forms that existed more than a billion years before animals emerged in the late Neoproterozoic.