British Soldier Lichen, Cladonia cristatella. It's only about ¼-inch high (6 mm). In this common lichen the red spore-producing reproductive structures are clearly visible. The lichen's name, Cladonia cristatella, is actually the name of the fungus. The alga species in the lichen is known as Trebouxia erici. However, it's customary to name lichen after its fungal part, so the whole lichen is known as Cladonia cristatella. British Soldiers are usually found on decaying wood, soil, mossy logs, tree bases, and stumps. They help break down old wood and put nutrients back into the soil where they can be used by plants. Lichens also take nitrogen from the air and put it into the soil so plants can use it.