This is a needle tip sample of a pyrenomycete fungus, as seen down a compound microscope.

 

In this image, you can just about make out that the individual ascospores in the asci have transverse and vertical septae (walls). These are known as dictyosporae. These kinds of characteristics enable you to key out the fungi to species (sometimes!).

 

I find the images I see down the 'scope incredible, for their aesthetic value alone, leaving aside the scientific interest. I hope you enjoy this short series, and others that I post from time to time, of some of them.