The absence of a mustache, that military symbol. And these symbolize the valuing of peace and non resistance. They are generally perceived as very positive symbols. To be seen to avoid smoking and dancing were, in my childhood Mennonite community, deliberate and self conscious symbols of separateness and higher values. Symbols are powerful and they are everywhere.
Words are symbols.
Graphic symbols are often complex ideas, compressed and made very portable. They are easy to remember and to use. They have impact and are recognizable from a distance. There is also, with them, both the risk and the benefit of being open to personal interpretation. Mennonites themselves have been symbols.