Unidentified eggs (millions of them!) any ideas?
If I was a betting man, I'd now lay odds that the jelly fungus you saw is the direct cause of the "eggs". Of course, fungi are strange beasties - your "egg mass" could just sit there as it is for an awfully long time if nothing shocks it into producing fruiting bodies. As you can't dose it on carbon dioxide, try producing another kind of local catastrophe - soak it to pretend that there's about to be the best flood since Noah. Keep soaking it over a few days to see if you can induce it to think that the end of the world is nigh. It'll either kill it (which I doubt) or you'll see it change form and erupt into the final stage of whatever it is. If nothing at all happens, then I'd dig it out and chuck it away on the grounds that it's inert (leaving us all frustrated and still guessing, I guess).