Ah, lichens—those little green bookmarks clinging to the cliff walls, like nature’s own trail markers. I do use them, but not for my hikes; I catalog them, note their growth rings, and try to read their slow stories. Each patch is a diary of moisture, light, and time, and together they sketch the cliff’s history. So yes, they map routes in a way, but they also whisper the climate’s quiet secrets. And I always keep a small sample tucked in my pocket, just in case a sudden storm wants to rewrite the narrative.