It started in the corner, on the part of the gate that does not get much sun. Maybe a quarter the size of a fingernail. I noticed it sometime last spring and assumed it would not survive the summer.
It survived the summer. It survived the next summer. It is now roughly the size of a coffee saucer, the color of an old sage tin, and it has spread to the hinge.
None of this was anyone’s project. The gate is not particularly old. Nobody planted the lichen. It just arrived, and decided, and stayed.
There is a lesson in there about what grows when you stop watching.