Lichen (Caloplaca heppiana)
Lichens are a headache for me when it comes to naming them. I think they are fascinating organisms but have they a structure and accompanying language of their own which I struggle to undertsand! There are several of these orange, crusty ones so I have to use all the powers of deduction I have to try and make an educated assessment of what each is nad, as far as I can tell, this is Caloplaca heppiana.
C. heppiana is very common on calcareous rocks rather than bricks (see Candelariella aurella) and forms even, closely compressed oval shapes with large orange disks in the centre. More orange in colour than Xanthoria periatina which is also very common but more so wood substrates. Telling it apart from Caloplaca saxicola is more difficult but I that seems to grow in to a larger, less even shape.
So, for me, this has to be Cladonia heppiana but do tell me if you think I am wrong!
Find out more about the nature of Dorset at my website www.natureofdorset.co.uk