The use of symbols to represent words & unspoken concepts, set mood, tone etc is common. Only those symbols most often used or of unusual interest have been included here. Many more can be found.
! [The Adventures of Tintin: Explorers on the Moon, 1954] An indication of surprise, wonderment etc
$#!* [Pitt #1, 1993] A disguised swear word "Holy $#!*! He's still standing!!"
@$$#*!# [Pitt #1, 1993] A thinly disguised insult word "Have you been an @$$#*!# all your life, or is this a recent development?"
...... [G.I.Joe vol.1 #104, 1990] Signifies waiting
? [The Adventures of Tintin: Explorers on the Moon, 1954] Signifies puzzlement or the condition of not understanding
[The Adventures of Tintin: Explorers on the Moon, 1954] Musical notes, as made when whistling