Pseudomicrofossils and authentic microfossils occur in the approximately 1.3 Ga-old Appekunny Argillite, lower Belt Supergroup, Glacier National Park, Montana. These microstructures occur in finely-laminated, dark gray and black mudstones that were deposited in an offshore environment and were subsequently subjected to moderate burial metamorphism. The pseudomicrofossils consist of 0.1–0.3 μm thick organic envelopes that encapsulate 1–20 μm diameter authigenic crystals. These crystals, petrographically identified as apatite (Ca 5(PO 4) 3OH, F, Cl) occur isolated, in clusters, and in filiform aggregates up to 200 μm long. The organic envelopes apparently originated through the accretion, around these crystals, of organic matter which was finely disseminated throughout the sedimentary matrix. The authentic microfossils are poorly preserved sphaeromorphs which, unlike the pseudomicrofossils, are highly compressed parallel to lamination. These microfossils are several tenths of a micrometer to ca. 1 μm thick and range from 22–82 μm long and 17–71 μm wide. They commonly exhibit tears and folds that evidently were produced during compaction of the enclosing argillaceous matrix. Due to poor preservation, these specimens cannot be assigned to known Proterozoic sphaeromorph genera. Inasmuch as the pseudofossils could be misinterpreted as microfossils, they well illustrate the need to exercise caution when interpreting organic microstructures preserved in Precambrian strata. Not being compressed parallel to lamination, the pseudomicrofossils are readily distinguished from the authentic microfossils which are strongly compressed parallel to lamination. The authentic microfossils demonstrate that organic-walled microfossils can be preserved in strata subjected to moderate burial metamorphism, and they provide information useful for recognizing and interpreting microfossils in similarly metamorphosed argillaceous strata.