Pyrenula punctella

Here the black carbonized cavity walls outline the fruiting structure of Pyrenula punctella. The black lines inside the cavity are spores aligned within asci. Those on the left side are dried and aborted as are some on the right. At the middle right side are some matured spores with one already escaping its ascus. The ostiole is at the top of the photo but is interrupted by the cavity wall.                  

Like many lichens, the fruiting bodies of the cavity are bound together by a substance called the hymenial gel. This turns orange when exposed to an iodide solution.