Not quite as simple a question as it sounds: Why are coins round?
My two favourite British coins are the 50 p and the 20 p. Both are round but they have edges. So I am delighted with the new One Pound Sterling design. You’d be able to identify it in the darkest of darknesses, just by fingering it. Yet, it too is, more or less, still round.
Why not a square, an oval, or a really long coin? A thick one, a wafer. No, not an invisible. That won’t work.
Let yourself get carried away in a dreamy moment and you might wish to speculate on the hierarchy of coins: Gold, silver, brass. And, yes, that sweetest of coins, the penny – in any country’s denomination – does hold a special place in my heart.