Lake Undozero Lake Undozero Lake Undozero () is a freshwater lake, located in the west of Plesetsky District of Arkhangelsk Oblast in Russia. It is one of the biggest lakes in Arkhangelsk Oblast and the second biggest one in Plesetsky District. The area of the lake is , and the area of its basin is . Lake Undozero is the source of the Undosha River, which belongs to the river basin the Onega River and thus to the White Sea basin. The lake has a sophisticated shape and contains a number of islands. The source of the Undosha is in the south-western
Onega stepanovi by an undivided zone. The surface of the undivided region of "Onega" is covered with small tubercles. "Onega" was originally described by Mikhail Fedonkin as a problematic organism, being grouped together with "Vendia", "Praecambridium" and "Vendomia" as possible stem-group arthropods due to a vague similarity with primitive Cambrian trilobites and arthropods. In 1985 Mikhail Fedonkin erected Phylum Proarticulata, in which he placed: "Onega", "Dickinsonia", "Palaeoplatoda", "Vendia", "Vendomia", "Praecambridium" and "Pseudovendia sp.", although he did not exclude the possibility that "Onega" may still be related to various lower Cambrian arthropods, such as "Skania". Andrey Yu. Ivantsov has proposed that "Onega" be