How the rule works
Something moves the same number of steps from cell to cell: a dot walking around the edge, arrows turning a fixed number of degrees, a figure changing place in the grid. The direction can be one thing to the right and another downwards.
It is a rule about position, not about shape. The figure is the same in every cell; only where it stands or which way it points changes. Anyone looking at what is drawn instead of where misses it.