this pentagram is turned upside down. as we know this represents satanism. But byside all psychoanalysis what's really interesting is the point that the pentagram was the symbol of illegal wisdom during the persecution of apocrypts by the roman catholic church. It's the symbol of the Knights of Templar, the Rosicrucians and finally the Freemasons who still claim to be the successors of the knights of the temple who have been excommunicated on Friday, October the 13th, 1307 by the pope.
technically/mathematicly the pentagram is also very interesting (that's the reason why it was a symbol for secret, prohibited wisdom). The proportion of the segments of one side is equal PHI, a mathematical constant, also known as the socalled
"golden ratio", a proportion that is found everywhere in nature.