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.
Onega River Monastery on an island in the Lake Kozheozero. Some of the finest monuments of the northern wooden architecture are located in the basin of the Onega, including ensembles of Lyadiny, Saunino Pogost, Krasnaya Lyaga, and Bolzhaya Shalga. These monuments also suffer from the lack of protection and their number steadily diminishes. In fact, the majority of them have been lost. The river splits into the Big Onega and Little Onega Rivers from its estuary, but then these branches join again, forming a big flat island. It freezes up in late October - early December and stays under the ice until