I once went into the loft space of my house, and found that in 1949 the guy pointing the brick chimney stack had written his name on it.

How many times in the last 75 years has that name been seen? Probably only a handful. That guy is probably dead now, but his name will be on my chimney for decades to come.

Maybe these people had the same instinct? Crawl somewhere deep and rarely seen and leave a mark. They probably also left marks everywhere else, but they're gone now.