Lichen on rocks, possibly <i>Xanthoria parietina</i>, in Bardon Mill, Northumberland, England.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/fire_brace/">Keith Hall ("pyrator")</a>, UK
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/fire_brace/231930506/">flickr.com</a>