Heptagram
The protective circle used to trap Meg in Devil's_trap contains a Heptagram (also known as a septagram, septacle, or seal of babalon), with a hexagon, two circles, and the image of a scorpion.
A Heptagram is a seven-pointed star drawn in one continuous line, in the manner of the five-pointed Pentagram. It can be found in the holy seal of the Brotherhood of the Silver Star, and the seven-sided design of most sheriff's badges.
The Heptagram is also found in Western kabbalah, where it can be a symbol of the seven notes of music, the seven colours of a rainbow, the seven planets, the seven alchemical metals, the seven days of the week, and the sphere of Netzach.
Wiccans of the Faery tradition and the Blue Star Wicca tradition also consider the symbol sacred. In more recent years, Otherkin have adopted the design.