This photograph is taken with the 25mm f2.5 Minolta Micro lens on bellows, used at f5.6 with studio flash. It shows the crud which is present on a 5-year-old CompactFlash card's connector strip - this is what the holes in your CF card look like. Most of this is probably human skin debris, but the large green globbet of fairy snot is a mystery. This is probably from the gremlin waiting to cause problems in your DSLR; gremlins have a serious phlegm problem, even very small ones.