Cephalozoa

Cephalozoa[1] are an extinct class of primitive segmented marine organisms within the Phylum Proarticulata from the Ediacaran period.

They possessed bilateral symmetry and were characterized by a thin, rounded body.

Unlike the other classes of proarticulates, the segmentation of the body is not complete and shows a "head" with fine distribution channels.

Some species of the Yorgiidae family also show some asymmetry.

[3][4][5] They were discovered in Russia near the White Sea in the Arkhangelsk region, where they lived during the Ediacaran, approximately 635 to 540 Ma (millions of years ago).

Yorgia waggoneri organization diagram.
Fossil of Andiva ivantsovi .