In villages across Northern England, as many as 20 miniature versions of the Easter Island head sculptures have been mysteriously left on doorsteps outside post offices.

Each of the carvings, some as tall as 18 inches, is slightly different, yet they all bear the same riddle on a blue note card: “Twinkle twinkle like a star, does love blaze less from afar?” The word “paradox” is written around the points of a star.

Authorities suspect that it is a publicity stunt of some kind, but so far no clues have been found as to the identity of the head carver.

Security camera footage caught a glimpse of a man getting out of a car, but his face was unrecognizable. He has been leaving the heads on doorsteps since August.