I had once a dream where a wise man told me to stare at a wall which was illuminated by a spotlight.
He put a little object in between, and it casted a perfectly round shadow on the wall.
Then he spun the object and the shadow shape turned into a perfect square.
Eventually he spun it for a second time and shockingly it casted a perfectly equilateral triangle.
Could you guess how did the object look? (I have deleted the STL preview in order not to spoil you)