Welcome back
Thanks :)
That thing you're asking about is called a summit register. They usually contain a roll of paper and a couple pencils so you can record your name and the date you summited if you so desire. I don't know if this is a common practice in other parts of the world, but it's pretty normal to find these on high summits in the US. I've found records from people going back as far as the early '80s. It's really quite interesting.
Incidentally, this register is one of the sturdiest ones I've ever seen. It's made of heavy duty PVC pipe with threaded caps… you could probably drop one of those boulders on it and it would be fine. Plus it's actually anchored to the rockpile with stainless steel cord to keep the wind from blowing it off the mountain. A lot of summit registers are just little glass jars crammed into crevices between rocks :)
Cheers. So it is a bit like geocaching for mountaineers :)
It is pretty cool that these even exist. I thought by now it would all be on an app.