Fungus? Heavens, no!
4 Different 105mm f/2.5 lenses, 1 sonnar type and 3 gauss design.
True one needs the front element cleaned.
It looks like D'Artagnan (the youngest of the lot) is the one who got bruised most, while the older of the lot (NKJ, the fattest one, maybe Porthos?) is the one in better shape...
I have 3 NKJs and a 1977 Nikon ("K" series), plus (naturally) the 105DC/2. Now that I think about it, the 105mm focal length is the most abundant in my collection: I also have the 105 uNikkor/4 AiS (MF), and the AF-D uNikkor 105/2.8
Ciao from Massimo