Crustose lichens are crust-like lichens that grow tightly attached to a their substrate which can be bark, rock, soil, fences, roof shingles.... The white one pictured here is on tree bark; different crustose lichens can come in many colors. From a few feet away, this lichen looks simply like a white patch on the tree. Bring a 10x magnifier into the woods (or into the Native Plant Garden) to discover the wonders of lichens.
The round cups in the closeup are called apothecia; they're the spore-bearing structures that allow for reproduction.