Rainbow Jellyfish are passive Mobs found in the Shipwrecked DLC. Similar to regular Jellyfish, they float around in the Ocean, sometimes in groups. They will not attack the player or flee if they are approached. They will not shock the player on contact as regular Jellyfish do. Once killed, their carcass will float in the water until picked up.
Rainbow Jellyfish can also be caught alive using a Net or a Trawl Net. As inventory items, they can be murdered by right-clicking them to produce Dead Rainbow Jellyfish. A Rainbow Jellyfish placed on the ground will immediately turn into a Dead Rainbow Jellyfish. They will have a short animation where they twitch twice before settling.
Rainbow Jellyfish can be cooked to make Cooked Rainbow Jellyfish, while Dead Rainbow Jellyfish can be dried on a Drying Rack to obtain Dried Jellyfish. Rainbow Jellyfish cannot be used in the Crock Pot. They can be eaten to glow rainbow colours in order to keep Charlie away, lasting for about 3 segments. The glow becomes weaker as time passes, until fading completely.
During New Moon nights, Rainbow Jellyfish migrations take place. They will spawn in large groups at the Volcano and migrate towards the middle of the Map. After the migration takes place, Rainbow Jellyfish will return to the Volcano. 
- Rainbow Jellyfish were added to the Shipwrecked DLC more than a year after its official completion in the Home Sea Home update, after being tested in a beta branch for several months.
- Verified via the Code found in components\rainbowjellymigration.lua