Brb I Gotta Take My Blog For A Walk

There was an ancient belief among Basque people regarding lightning: they thought lightning was lead to earth by a heavenly stone that would fall from the sky. 

This stones were called tximistarri (lightning stone) or ozpinarri, ozkarri, ortzarri or oneztarri, all of them variations of Oz’s stone. Oz - also spelled Ost, Ortz, Ortzi or Urtzi - was the Basque god of the sky. After Christianization, they were also known as Santiago harriak, or St. James’ stones.

Since these stones came from the sky, they were presumed to have powerful protective properties, so Basques would usually look for them. And in their search for tximistarriak, they would find sea urchins fossils:

Their strange shape made our ancestors believe that it was in the center of that star where the lightning stroke following the stone to earth. After Christianization, their star-shape was seen as a labarum.

Be it of Pagan or Christian origin, in some places of Euskal Herria it’s still a tradition to keep these tximistarriak or calvarris - this might come from Basque “bald stone” - at home.

Satan costume. Ameline, role de Satan, dans “La poule aux oeufs d’or.”  ca. 1848.