I found a a few versions of the Petersen coat of arms/crest online, did a bit of research on the origins of the Petersen name.
The name spelt Petersen and not Peterson, found mainly in the north western European countries of Denmark, Holland, Germany and Brussels, and also further north in Finland, is a patronymic from the male given name Peter, itself ultimately coming from the Greek petros, meaning "rock" or "stone".
Coats of Arms granted to the Petersen families of Greiffenberg, (Prussia); Hesse, and Finland are recorded heraldically in Rietstap's "Armorial General", the former depicts the upper body of a stag leaping from the centre of a blue shield. A silver cross moline is the base.
The first recorded spelling of the family name is shown to be that of Petersen of Prussia, which was dated circa 1680, Rietstap's "Armorial General", during the reign of Emperor Leopold 1, "Habsburg Emperor", 1...