Medusinites
Medusinites is a genus of disc shaped fossilised organisms associated with the Ediacaran biota. They have been found in rocks dated to be 580 to 541 million years old. Biology. Only three distinct species of "Medusinites" are known. They are similar to "Protolyella" in form and have an inner and outer ring. Specimens are typically 1–5 cm in diameter and the radius of its central disc is smaller than the width of the outer ring. They also have radial furrows and concentric circle features, but those details are not always preserved. They have been described as possibly living a  lifestyle similar to a "stationary intermediate-level epifaunal osmotroph". Distribution. "Medusinites" species have been found in Australia, Canada, Norway, India, and Algeria. They are often found in sandstone and quartzite. Classification. "Medusinites" are in the Phylum Cnidaria, which means they are related to other genera such as Aspidella and Cloudinidae, and are essentially classified as eumetazoans, just like modern jellyfish. However, there have been several differing theories over the years about the placement of "Medusinites", as well as the Ediacaran biota as a whole, and how many species there are within the genus. Several species within "Medusinites" have been moved  to other genera or absorbed into other existing species, such as "M. patellaris", which was found to be a junior holotype for an Aspidella sp., and "M. mawsoni", which was assimilated into "M. asteroides". Regarding the debate over the nature of disc shaped Ediacaran fossils like "Medusinites," there are two main opposing points of view"." A. Seilacher views the theory of them being soft bodied and jellyfish-like as problematic and suggests that they were more likely a unique type of organism that had a "quilted" construction. Another view supported by Grazhdankin and Gerdes is that they were possibly a  type of microbial colony.