Cyclomedusa

The concentric disks are not necessarily circular, especially when adjacent individuals interfere with each other's growth.

The fossils have been conjectured to represent a holdfast for some stalked form — possibly an octacorallian, or something else entirely.

It is now suggested that Cyclomedusa was a microbial colony;[5] D. Grazhdankin reinterprets the concentric rings and radial structures as comparable to those seen in modern-day microbial colonies exposed to homogeneously distributed environmental conditions.

Cyclomedusa is known from Neoproterozoic beds in Ediacara (Australia), Finnmark (Norway), Charnwood Forest (England), Olenek (Russia), North China, Newfoundland, Northwest Canada, Podolia (Ukraine), the Ural Mountains (Russia), the White Sea (Russia), Sonora (Mexico), and Ceará (Brazil).

[6] It is regarded as a member of the Ediacaran biota— a group of somewhat obscure organisms that thrived just before most of the modern multicellular animal phyla appeared.