Thanks a lot! The mossy clumps are Aegagropila linnaei (actually a green algae).I'm a bit late to the party and only just discovered this thread. Really loving the latest "Succession" in the image above.
JEK, can I ask, and please excuse my ignorance and lack of knowledge, what are the mossy clumps at the bottom right and leading down from the rocks?
C. pygmaeus added - only 4 so far (long story), but the plan is to get at least twice as many.