Onega stepanovi placed in phylum Proarticulata, as the segments in recently discovered, exceptionally well-preserved fossils display the glide, or "staggered", symmetry characteristic of the majority of proarticulatans. Imprints of "Onega stepanovi" have been found in the Verkhovka and Zimnie Gory Formations of the Ediacaran (Vendian) rocks of the Arkhangelsk Region, Russia. All the fossil specimens are negative imprints on the bases of fine-grained sandstone beds with the "elephant skin" and tubercle texture diagnostic of microbial mats. The same bedding planes contain various other Ediacaran species: "Cyclomedusa", "Ediacaria", palaeopascichnids, "Eoporpita", "Yorgia", "Andiva", "Archaeaspinus", "Vendia", "Dickinsonia", "Anfesta", "Albumares", "Tribrachidium", "Kimberella", "Parvancorina", "Charniodiscus" and others.
Lake Onega months. The highest water level is in June–August and the lowest is in March–April. Rivers bring of water per year to the lake, that is up to 74% of the water balance; the rest is provided by precipitation. Most of the lake water (84% or per year) outflows via a single River Svir, and the remaining 16% evaporates from the lake surface. There are frequent storms more characteristic of a sea than a lake; waves of are not uncommon and may even reach . The lake freezes near the coast and bays in late November and December and around mid-January