What are these clusters of branching structures on/in my lens?

I packed a Tamron 28-75 lens away for over a year. When I took it out of storage examined it, I found clusters of branching structures on or in the front element.

I Took it to a camera store and they said it wasn't fungus, but they didn't tell me what it was. I have removed the front element and cleaned the backside but it does not fix the issue.

It does not impact picture quality at all. Not sure what to do.