OK...Who has been leaving choice little object d'art around our walking tracks? And why?

On my routine walks I have noticed these little rock d'art in placed in choice but discreet spots not far off the tracks I generally walk. I have only found two, but hope to find more! I would encourage more as they are delicately and very well drawn......WELL DONE FUN!

Also....don't forget the fireflies are out - 5:30-6;00PM walks in the bush are the go as there are quite a few levitating around.