Possible stem cnidarian at ~600 Mya

https://onlinelibrary.wiley.com/doi/10.1111/pala.12242
"Abstract
The early Ediacaran Lantian Formation in South China contains some of the oldest known representatives of morphologically complex macroorganisms, including various macroalgae and putative animals. The macroalgal fossils have been described previously in several publications, but no taxonomic treatment has been published for the putative animal fossils. This hampers our ability to fully evaluate and communicate the significance of these potentially important Ediacaran macrofossils. To address this deficiency, here we provide a systematic description of these putative animal fossils from the Lantian Formation, including four new genera and five new species: Lantianella laevis gen. et sp. nov., L. annularis gen. et sp. nov., Piyuania cyathiformis gen. et sp. nov., Qianchuania fusiformis gen. et sp. nov. and Xiuningella rara gen. et sp. nov. Morphological comparisons of these fossils and potential modern analogues are provided and critically assessed."
This is an article I missed (2016) that describes very-well preserved fossils in the Lantian formation.  Among other hard-to-assign specimens is a conical specimen consisting of a basal holdfast and topped with structures strongly suggesting tentacles.  The resemblance to cnidarians is unmistakable.  The authorship has strong credentials in Ediacaran research.