So, I stopped into a local photo/camera shop to see if they had any used equipment; MC/MD lenses in particular. The guy behind the counter pointed out a glass case near the back and said to check it out. The first thing that I noticed was a big MD Rokkor-X 80-200 f/4.5 that was marked down from $150 to $89. Then, behind a couple of others, I spotted what appeared to be another MD lens, but I couldn't see the markings to know what it was. When the man passed by, I asked to see those two. He pulled them out and started looking through to see if there were any others. My curiosity made me check out the mystery lens first. It was a pristine (other than a couple of white marks on the built-in hood) MD Celtic 135mm f/2.8. I held it toward the light and used a small flashlight to look through it. Except a couple of very small dust particles near the edge, it was pristine on the inside, too. Then, I checked the 80-200. To my dismay, there was a white growth near one side on a middle element. I pointed it out to him and after looking through it himself, he agreed and actually sounded quite sad about it. He did, however, show me a nice Sigma 80-200 f/4.5-5.6 that he had found. It was significantly smaller (in part due to Rokkor's constant aperture, but also its age) and, upon inspection, was found to be totally clean, too. So, I asked how much for the Celtic and the Sigma. He thought a bit and said $75 for the two. I hesitated for a moment and he added "and I'll throw in this one," indicating the Rokkor. "Try it. If it doesn't work, no loss; if it does, use it until it doesn't. I'd rather have you get some use from it than have it sit around getting worse." Deal! I did try it briefly and the fungus doesn't seem to affect images yet (thanks to the :43: center crop), so I'll have some fun with it until it grows too much. All-in-all, 2-1/2 lenses for a fraction of a :43: one. I'll add pics to the "Show us your adapted lenses" thread. Side question: is fungus in any way contagious? To other lenses, I mean. In other words, should it get its own separate spot?