Primorsky District, Arkhangelsk Oblast and with Onezhsky District in the south. From the north, the district is washed by the White Sea. The area of the district is . Its administrative center is the city of Arkhangelsk (which is not administratively a part of the district). Population: The district occupies the lower course of the Northern Dvina River and the White Sea coast around the Dvina Bay. The waters of the district drain into the Northern Dvina and the short rivers of the Dvina Bay basin, such as the Shirshema and the Lodma. The eastern part of the district is a plateau which drains
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.