Lichen

A very wet day with barely a break in the rain. 
I know almost nothing about lichen, but thought it might look interesting with a macro lens. It's growing on a piece of sandstone that holds down a metal heron that was bought to deter real herons. It never lived up to the advertising claims, but one of the robins likes to perch on it. It's one of several small areas of lichen that I think add colour and texture to the alpine bed. I don't know if lichen's a good or bad thing to have in a garden. I just know that I like it.