The tiny, delicate plants spend most of their year in the vegetative state but in late winter they enter their reproductive phase and produce microscopically small egg cells inside flask-shaped structures called archegonia hidden amongst the leaves, and also minute containers of male sex cells called antherozoids.
The antherozoids swim in the surface film of water on the leaves, frantically heading for the archegonia that release a chemical attractant. A surface film of water is essential for successful sexual reproduction in these plants. When the sex cells fuse a spore capsule forms, filled with minute spores, and when it's ripe this elongates on a two inch-long stalk, often overnight............and ......
.............. that's what these are - a forest of ripe Lophocolea spore capsules, like little black beads, already beginning to burst and shed their spores (the white fuzzy structures are burst spore capsules). In another day they will all have shed their spores and withered away, their reproductive phase over for another year.
Although their reproductive season is short livrworts been around for about half a billion years, surviving five great mass extinctions that have wiped out many other life forms. Fragile plants, but durable within the great evolutionary time scale.