There are many pages, blogs and forums about lens fungus in the internet. There you can read and see how he looks like, what he wants and what he does and how you can perhaps remove or eliminate him. The most people don't like fungus in their lenses.
But in contrast to this attitude, I want to show what effect he makes in the pictures.
I bought many of my cameras and lenses on flea markets in Germany. And of course the lenses of all my cameras didn't have fungus.
But I moved in 2007 to Brasil and after some months a part of my lenses got fungus inside. First I was very angry and desperate, but after a while I decided that fungus isn't the end and had the idea that fungus can be a great new effect.
I took many photos with the fungus lenses, but on the pictures you can't see any effect. After this experience I can't understand the people who upset with lens fungus.
But I didn't want to abandon the idea to find a way to show the fungus effect. I've tried many things and found the way how you can fix the fungus effect on your pictures.
It is the same way which I used to make double exposures with a DSLR.
Now I've used my Leica R4 and the Elmarit 2.8/35mm lens (at f-stop 2.8), both I bought in Brasil. The fungus in the Leitz lens is small and has got a nice structure. The flash was the Metz Mecablitz 20BC6.
Here are the pictures: