Bottom, right, 4th up, weird logo, oval, line, 3 slashes, what is that logo?
It's curious and unexpected. It's an ogham letter, called ngetal, representing the sound of "ng." Ogham is writing system used primarily by the Irish back in pre-Christian times, but also found among the Scots, back in the days when the Druids wouldn't put things in writing. It was considered a mystical or magical alphabet, and seems to have been used almost exclusively on stone boundary markers.
Actually, there were around 75 systems of ogham, some written, several systems of sign language, and others consisting of verbal clues.
There was, and still is, a great deal of interest among mystical groups, and also among antiquarians, beginning in the late 1800s.
A verbal cue system seems to have been the inspiration for a British code system in WWII. The code was never broken.