Nimbia

Nimbia is a genus name given to a common enigmatic discoidal fossil form known from the Neoproterozoic and possibly into the Cambrian, found on multiple continents including Russia, Ukraine, India, Brazil, Morocco, China, Spain, Norway, Canada, and the United States. Specimens are discoidal, typically fifteen to forty millimeters across, usually flat with thickened margins, and some show concentric rings or central features. Its true biological affinity is unresolved: researchers have proposed that Nimbia fossils represent simple microbial colonies, simple cnidarians, or the holdfasts of a larger organism such as those seen in the phylum Petalonamae. The type species is Nimbia occlusa, described by Fedonkin in 1980 from Russia White Sea coast.