This particular rock (on the Buna Vista Course in Switzerland) which you can just see in the middle of the fairway has a multiple purpose.
From the Tee, which is an eagle's nest about 80 feet above the landing area, it acts as a hazard for the long players – especially the ones that claim to have hit it with “a perfect shot”.
.... but probably more important the rock serves players who aren’t quite long enough, like the 2 in the picture, an oppurtunity to align the green approach, which becomes blind the further one is towards the farm track.
However the main reason the rock is there - is because after much excavation we finally hit bed rock, and rather than bring in the heavy machinery or explosives I thought it would add more strategy (and controversy) to the hole if we left the rock as it be, exposed at the surface.
Up to now the “quirk” is appreciated by the majority of golfers.
