Elephant skin

Well, it isn't really elephant skin (you guessed?) But I do love its texture and the old grey whistletest wrinkledness of it.
I also think it's quite fun sometimes taking macro pictures of things in a recognisable habitat. So here are trees in the background, as reflections in the water and as a branch for the lichen to grow on and hang from, which repeated pattern gives me a childish amount of pleasure.
Besides, after my rather exhausting day yesterday, struggling to the river on my hands and knees looking spry and got together was about as much as I could manage.
I'm hoping Tuath can tell me what this lichen is called. Plants and trees I can mostly do, but not lichens!