Tursaansydän means the 'heart of Tursas' and in Finnish mythology, Tursas (alias Iku-Turso and a few other names) was a rather unpleasant sea-monster that supposedly looked a bit like a bearded octopus. Another name for the same symbol is Mursunsydän, which means 'heart of the Walrus'. For a long time, especially in Northern Europe, the symbol has been considered a Good Luck charm.
Finnish Knot - Ancient Finnish symbol - Hannunvaakuna - Kalevala Koru - Good Luck symbol
Saint John's Arms - Finnish and Swedish Looped Square