“The looped square is a symbol consisting of a square with outward pointing loops at its corners. It is referred to by this name, for example, in works regarding the Mississippian culture (approximately 800 CE to 1600 CE). It is also known as the place of interest sign when used on information signs, a practice that started in Finland in the 1950s and spread to other Nordic countries in the 1960s. Also, the symbol is known as Saint John’s Arms or Saint Hannes cross (related to Swedish sankthanskors, Danish johanneskors, and Finnishhannunvaakuna), as Gorgon loop, and as the command-key symbol due to its use on the command key on Apple computer keyboards.
It is an ancient symbol used by several cultures and remains in common use today. It belongs to a class of symbols which are called valknute in Norway. The symbol appears on a number of ancient objects in Northern Europe. It features prominently on a picture stone from Hablingbo, Gotland, Sweden, that was created between 400 and 600 AD. It is also similar to a traditional heraldic emblem called a Bowen knot. In Finland, the symbol was painted or carved on houses and barns, and domestic utensils such as tableware, to protect them and their owners from evil spirits and bad luck. The oldest surviving example is a pair of 1000-year-old (Finnish pre-Christian period) wooden skis decorated with the symbol. The looped square also appears on artifacts of the Mississippian culture of the southeastern United States. While not a true knot, many depictions follow the convention for heraldic knots in that the crossings of the strand obey an under-over pattern.” (Wiki)