As regards Jellyfish and Jews:
To be kosher, a fish must have both fins and scales. The lack of either characteristic renders that species of fish unclean. Examples of unkosher fish include shark, catfish and eels. All shellfish, such as crabs, lobster, and shrimp are not kosher. All sea mammals, such as dolphins, whales and seals are not kosher. All other sea animals, such as octopus, squid and jellyfish are also not kosher.
Seaweed and other sea plant life are all kosher.
There are two fish that are controversial: Swordfish and sturgeon. Both of these have scales as young fish, but lose them later in life. Most Orthodox rabbis rule that these fish are not kosher; many Conservative rabbis rule that they are kosher.
I could kick myself. It's so obvious that I should have thought of it. Still, we live and learn