Livingston as a jellyfish
A jellyfish was an aquatic animal originating from Earth.
In 2370, the lionfish Livingston de-evolved into a jellyfish as a result of suffering from Barclay's Protomorphosis Syndrome, although it later recovered. (TNG: "Genesis")
Lieutenant Sylvia Tilly called the Tuscadian pyrosome a "jellyfish from hell". (DIS: "All Is Possible")