@CiaraNi I don't think there's any point of reference, I'm simply reminded of a very interesting mulberry tree that an old friend and I once discovered close to a similar wall.
We had never seen a mulberry tree before. There were loads of birds in the area, the tree was laden with berries, plus masses of berries on the ground beneath it. We didn't know they were mulberries. All we knew was that the birds went nowhere near them, so we assumed that the berries were poisonous, and (me being me) eventually I decided to eat one.
A passer-by (it might have been someone who was photographing bricks) saw us looking confused and approached to tell us the story of how the mulberry tree arrived; and why the birds simply knew not what to do with it.