This recent photo of moss spore capsules shows they are ready to release their spores. The lid (operculum) that covers the end of the capsule has fallen off, an indication that the spores are ready to be released. The peristome is composed of flexible teeth that gradually disperse the spores from the stoma (mouth). This species of moss is growing on a rotting log in a deciduous woods in Iowa.
I think moss spore capsules are really cool. The little insect in the upper left of the picture is especially cute. This photo was taken on the way up to Annapolis Rock, Maryland, along the Appalachian trail, on a hike with my mother while I was in high school.