Tubes In The Swamp Of Brief Dispair

Today when I was watering things in the greenhouse (well, checking that they had been watered properly by the sprinklers) I looked a little closer at my "Swamp Of Brief Dispair". In the mirrorlike "Pool Of Dunking Plants That Have Dried Out In Their Pots" I noticed these fascinating tube like structures all over the bottom. No idea what they are, any suggestions?

Also of note is the development of some ferns on the sphagnum moss bed:

and the first of the mosses on the living wall: