"What are these solid white domes of varying sizes the one pictured here is about a meter high and meter wide though some were bigger. Found all over the Andalusian region of Spain. They’re solid with no openings and seem to be made of some sort of solid rendered material maybe concrete."
A: "Lots of European countries have things like these as tank-deterrents left over from WW2."
I have one for each of my extension cords.
Pur coals inside and then place under covers.