Edited: Thyme and Allied Mosses (Genus Plagiomnium). See ID thread. I initially suggested that this was outside my experience: possible Leafy liverwort of Genus Chiloscyphus or Cinclidium?. Leafy liverwort (Genus Chiloscyphus) is reported from this geographic area, but I am not confident about my ID. Occurs on dark, damp, vertical dolostone slab substrate, Duncan Crevice Caves, ON, Sept 14/22. See discussion at: https://inaturalist.ca/observations/147260571