assemblage of microscopic fossils uncovered in the Gunflint Iron Formation, a rock layer about two billion years old exposed in western Ontario, Canada. The fossils include filamentous structures resembling blue-green algae (e.g., Gunflintia, Entosphaeroides, and Animikiea), tiny spheroids (e.g., Eosphaera and Huroniospora), star-shaped forms assigned to the genus Eoastrion, and umbrella-shaped forms assigned to the genus Kakabekia. These and other fossils were first collected near Thunder Bay, Ont., in the 1950s. Analyses yield strong evidence that some of these fossils are the remains of some of the earliest photosynthetic organisms.