What is this in the rear element?

Hi fellow Pentaxians,
once again I'm looking for some advice from more experienced photographers. I'm offered second hand Leica lens adapted to K mount for a reasonable price...but there's little catch in it. It has something on the rear element - see the photo. The seller thinks it is a fungus, but is not sure and neither am I. Does anybody know what it can be and how serious threat it may be for the proper functionality of the lens?

here's the photo:

I would be very thankful for your advice, as I am seriously considering whether to buy this lens or not. Besides of those particles at the edge of the lens, there is also small dot near the centre, but neither has the impact on the photos yet.

I'm not an expert but fungus is often filaments, certainly in the ones I've seen. It could be fungus but possibly it is evidence of lens elements separating where they are cemented together. This can be fairly common with some makes and models of lenses so maybe a Google search looking for lens element separation with the particular Leica lens you are looking at might turn up something that corresponds with what you're seeing.

Roy

Spots can mean lens separation. The cement between elements can fail, causing the marks. The worst one I ever saw was a Minolta CLE 28mm lens - there was a complete ring of large white spots.

Roy, John...thanks. I'm bit relieved that it may not be a fungus. Sure cement particles are annoying, but not as serious as the fungus eating through the glass, i believe. I'll do some quick research on lens element separation to decide how serious the impact may be.

If the elements are separating that will disturb the optical arrangement, so I wouldn't touch it. A lens repairer would be able to tell you better.