Smooth Rock Tripe - Umbilicaria mammulata
Large foliose lichen that was greenish brown on top and black underneath. They ranged in size from 5-10 cm. When weather conditions are dry, this lichen turns brown as you can see in this shot. When wet, it turns green. The brown zigzags on this lichen are damage done by slugs.
''Umbilicaria mammulata'', or Smooth Rock Tripe, is a foliose lichen found on boulders and rock walls.