Buried at Stonehenge are hidden bluestones, protected from the effect of weather and trampling feet by an earth cocoon.
Clearly these are shaped for purpose. The oval holes in the lintels provide clues as to how the doors worked.
How they fit with Stonehenge, when built, is illustrated below. The oval holes were formed to accept wooden tenon plugs. These were Bronze-age equivalents of today’s expanding rawl-bolts.