Ulota calvescens on rock

I found a single tuft of Ulota calvescens on a capstone of a roadside wall south of Cwmgors (i.e. the Nant-y-Gaseg bridge parapet immediately s.w. of the Abernant Tip turning SN70310858) today, which seemed a bit odd. Sure enough, when I checked I could find no reference to it growing on rock. I also found two tufts on an Oak trunk in Llewelyn Park, Swansea a week or so ago, so at least 4 Glamorgan sites now.