If you're wondering what I'm on about, I didn't know what they were either.
They are, it seems, the – usually – concrete pillars built by Ordnance Survey in 1936 to safely house their theodolites which are used for measuring the lie of the land.
If all that sounds a bit boring just look at some of the amazing photos of them bearing in mind most are situated very high up indeed.
I do rather like the Minion but my favourite is the one at Ben Ledi, Perthshire, with its stream of rime ice. Breathtakingly beautiful. But brrrr!
“There is always a well-known solution to every human problem - neat, plausible, and wrong.” H.L. Mencken