A speculation by a clever guy, delivered back in 1961. Now, this Sagan fellow figured out a lot of stuff that has turned out to be true and important, both here and above. More on that later, perhaps. But, back in the '60's, he was wondering if the clouds of ammonia and hydrogen in the atmosphere of Jupiter might seed life of a kind we do not yet know. Perhaps, as one of the ancient Greeks, Aristophanes, imagined, there was a Cloud Cuckoo Land, where creatures did float and play with beings below their loft closer to the stars.
Let's go find out.