Yep! That's fungus for sure. Among the different recipes for lens fungus cures abounding on the internet, the two most effective I have found are Pond's cold cream and a 50/50 mix of ammonia and hydrogen peroxide. The cold cream works, but it is sheer hell to clean it all off again (you have to work it into all the stuff near the lens too). That said, the peroxide/ammonia mix is the one I use. It just melts fungus away. The problem with most of the other "cures" is that they don't remove the mold growth -- they just kill it -- so half the time it looks like the mold has etched the glass and the lens gets tossed.