Wall decoration

This piece of art in plaster has been hanging on a wall in our home since we moved in.  Nobody has ever given it any comments - until very recently when our children's cousins started to speculate about its origin.  It's some kind of imprint - but of what or whom...

I plan to bring this blip to my photo club's meeting next week where we are supposed to interpret the theme "avtryck" in Swedish.  It could be translated to imprint and mark and probably something else.