Crustose Lichen (Lecanora dispersa)
If you stop at one of the bridges over the lower reaches of the River Frome, as well as plants such as Wall Rue and Maidenhair Spleenwort you will, I am sure, notice the extensive areas of crusty white stuff on the tops of the walls.
I find it hard to believe that this dried up and cracked substance is actually a living thing - in fact it is two living things; an algae and a fungus living together as one lichen.
I accept that it is not much to look at nor particularly exciting to find but, that said, I do find it fascinating. It is very slow growing and you can only stand and wonder just how old it is.
There are several similar species but I am fairly certain that this is Lecanora dispersa and you will find it on walls, tomb stones and calcareous rock substraits right across the county. It is very common and is very resistant to pollution and so has no problems growing close to roads even there there are high levels of toxins there.
Why not take a magnifying glass and go out and have a look at these crusty old things!