At Opal Creek Ancient Forest Center in Oregon, I scrape from a large rock, dripping wet with spring and covered in mosses, liverworts, and lichens, a clump of free-living Nostoc cyanobacteria, a glob of gray goo. I squish it between my fingers and think of the gelled contents of a discarded ice pack. Rolling it around, I discover, whoops, a little wriggling worm. Gray goo is a paradise to some of earth's creatures, but I tend to appreciate something more organised. On the same dripping rock, I find an intricately branched lichen, clear and gray like the goo, but sparkling like mouth-blown glass, delicately wrought into a shape resembling a network of rivers on a map, shrunk down to palm-size. This little thing of beauty, called jelly lichen, consists of Nostoc cyanobacteria too, but in combination with a Leptogium fungus whose hyphae have lent pattern, structure and stability to the raw photosynthesising power of the cyanobacteria. The form emerges from the relationship between the fungus and the cyanobacteria.