Hey, want to read several thousand Everett True comics? Look here: https://chroniclingamerica.loc.gov/search/pages/results/?date1=1777&rows=50&searchType=basic&state=&date2=1963&proxtext=Outbursts+of+Everett+True&y=13&x=19&dateFilterType=yearRange&page=1&sort=date
Pick one and post!
The sign was used by the Nazis, however the iron cross is older than them like alcoholicorn said. You can still see it on a decent amount of German military equipment.
Also not to mention in this context it’s supposed to resemble the x mark you’d see portrayed on treasure maps.