It would be's a matter of time whenbefore the scientists get to know the reason behind this jealous ability, then human beings could live forever.

With "jealous ability," I assume you mean that humans are jealous of it?

I heard about a unique type of jellyfish, known as anthe immortal creature.

We use ‘the’ because we’re talking about this specie of jellyfish in general, not one singular jellyfish.

It would be’s only a matter of time when thbefore scientists get to knowfind out the reason behind this jealousy-inducing ability, t. Then human beings could live forever.

If we say ‘jealous ability’, it’s like saying that the ‘ability’ is jealous of someone/something. Just like when we say ‘She’s a jealous person’, we’re saying that this person is jealous of someone/something. But we want to say that the ability itself causes jealousy, so we say ‘jealousy-inducing’.

This animal is called "Turritoopsis dohrnii".