Nazi concentration camp badge
Triangles appear on many postwar memorials to the Nazis' victims. These shapes represent the identification patches used in the camps. Sometimes, plain or colored triangles represent all categories of inmates. Often, inverted red triangles represent all victims of the concentration camps, including also the non-Jewish victims like Slavs, Poles, communists, homosexuals, Roma and Sinti, people with disabilities, Soviet POWs, and Jehovah's Witnesses.