Dust, separation or fungi?

To me, it looks like little bubble imperfections in the glass. I remember seeing a very similar photo and discussion of this years ago wrt the 70-200 f/2.8L (non-IS? or IS I, maybe the same lens   ) but cannot bring it up with search. I think it was determined to be a non-issue in the optical performance of the lens (but I could be wrong).

here's a similar discussion on the TS-E 24 f/3.5L II:

http://www.dpreview.com/forums/thread/2825122#forum-post-35637678

Kurono wrote:

Hello all, I have quite a conundrum and would like better trained eyes to help discern just what is inside my lens.

I just bought a 70-200 f/2.8 IS lens (Canon, MK I) used, and was performing checks on the lens. On the outside the lens seems to be ok, but when inspecting the inner elements I came across some weird dots on (in?) the glass which seems to be almost in the middle of the lens.

At first I thought they looked like bubbles, as they seem to be very evenly spread. My next thought was mold (gasp), but in my experience, mold tends to grow from the sides and looks like little tendrils. Granted, I've seen that mold can look like spots too, but not quite like these.

Anywho, I leave you with the images I took in a hurry right now. In the worst case scenario, I plan to get the lens into maintenance or for appraisal with Canon.

Thanks.

In this image, you can see that some spots are bigger, but those are out of focus (it seems they are on two contiguous elements).