Crustose lichen, Rinodina or Lecanora, on a back surface ...

The image shows a close-up view of a gray stone with lichen growing on its surface.

* The stone is a light gray color and appears to be made of marble.
* It has a rough texture and several small holes or cavities in it.
* There are no visible signs of damage or wear on the stone.
* The background behind the stone is not visible, but there may be other stones or objects in the area where the photo was taken.

The lichen growing on the stone is crustose, meaning that it forms a dense mat-like growth on the surface. It has a light greenish-gray color and appears to be quite thick in some areas.

* The lichen covers most of the visible surface of the stone.
* There are no other objects or features visible in the image besides the stone and the lichen.

Overall, the image provides a detailed view of a specific type of lichen growing on a piece of gray marble. – AI vision