It looks pretty much like fungus to me — the branching is characteristic. It might, however, not be fungus itself, but etching on the glass as a result of fungal growth.
It's true that fungal growth on lenses is generally all connected. That's not necessarily true, though. Fungus can grow from lots of different "starter" spots as well. This blog post shows an example of fungus growing this way, which I've excerpted here:
Of course, it's not as pervasive and there is more of a circular pattern to each "bloom", but this demonstrates that it's not always a big patch growing from the edge.
Meanwhile, I'd expect lens glue crazing to look more like a series of little lines, and not nearly so fractal. But I've never seen that in person either way.
One possible guess — and it's just a guess! — is that it was all connected and this is where it was enough to etch the glass.