British Soldiers (Cladonia cristatella) 2007-5-13 www1 Bombay Hook NWR, DE
This species has a "crusty" stem. There is another species, I think, with a smooth stem.
"British Soldiers, like all lichens, grows very slowly. It grows one to two millimeters each year."
http://www.fcps.edu/islandcreekes/ecology/british_soldiers.htm