This is the same phenomenum reported in _observation 102448_, three and a half years ago. As there, it seems that a Fulgensia sp. (with a yellow thallus) and another lichen (with bluish thallus), which could be a Caloplaca sp. live together. But it can be only a Fulgensia sp. whose thallus deteriorated for some reason. So, for definiteness, this observation refers to the lichen with bluish thallus.