Favoritos de flutterbyflutterby

• on siliceous metamorphic bedrock in the channel of Deep River; regularly inundated by high water
• black apothecia with prominant thalline rim

[EDIT, 11 August 2023: After finding on Rocky River an example of Placynthium nigrum with only its black prothallus yet with numerous black-rimmed black-disced apothecia, yet lower down with the muddy-green thallus atop the prothallus, did I eventually realize that all my Vahliella hookerioides observations were in fact Placynthium nigrum!]

This is the only species of Vahliella with a black apothecium.

This specimen is rather desiccated. In hydrated condition the thallus is of olive-green hue. Hydrated example at same location, same day: https://www.inaturalist.org/observations/166448585

Assuming it’s a lichen. Notice the light sky blue spots surround by solid black which seem to be surrounded by tiny white specks. Photo taken with a 15x smartphone macro lens zoomed in tight.
This is one of the dark discolorations on a concrete overpass. Stilesboro road over Alatoona Creek. So tiny that I could not see anything but the discoloration splotch and took a photo anyway. Very surprised to see the blue and details once home. I will return with measuring device. Hopefully better photos as well.
@mhodges1957 I haven’t a clue on this one. Can you point me in a direction?