Prepare the JELL-O® as directed. Pour the mix into small bowls and refrigerate until the JELL-O® is firmly set (at least 4-5 hours). These will be the jellyfishes' bells.
When the JELL-O® is firm, prepare the jellyfishes' tentacles. For each jellyfish, arrange gummy worms on a plate with the worms radiating outward.
Loosen the gelatin by dipping the bowl in warm water. You may also need to run a knife around the edges. Quickly flip the bowl over the plate of worms. Jiggle or tap the bowl until the gelatin falls out.