Shown is a soft-bodied fossil that was first described & named in the 1850s, but is still considered a problematicum in the modern literature. This is a soft-bodied frond called Plumalina plumaria Hall, 1858. Workers usually assign this organism to the hydrozoans (Phylum Cnidaria, Class Hydrozoa) or the gorgonarians (Phylum Cnidaria, Class Anthozoa, Order Gorgonaria), but it’s probably safest to refer to it as “Incertae Sedis” (“uncertain placement”).