Octomedusa is a genus of extinct scyphozoan jellyfish known from the Late Carboniferous sediments of the Mazon Creek fossil beds.

Young and Hagadorn also proposed the idea of Octomedusa as being a Narcomedusan Hydrozoan; although they did not give any explanation on why they assigned the Jellyfish to that affinity and even if the fossils belonged to the order Narcomedusae it would be within the subclass Trachylinae as opposed to the other Aequoreids which are found in the Leptomedusae.

[2] The species name, pieckorum, is in honour of the fossil collectors Mr. and Mrs. Ted Piecko who have helped donate the holotype and paratype of Octomedusa to a museum for further studies and scientific descriptions.

[1] A smooth and scalloped margin are present in specimens, however they were proven to be the result of artefacts made from preservation.

The preserved remains of the organism are so general that they were originally not able to be assigned to either the true jellyfish or the hydroids.