  In classical and quantum spin ice, rod-like features appear in the neutron
scattering structure factor when the pinchpoints characteristic of classical
spin ice get washed out. We show that these features do not indicate the
absence of spin correlations between planes perpendicular to the rods. Rather,
they arise because unpolarised neutron scattering is largely insensitive to the
three-dimensional correlations which are present throughout. We present two
very simple models which exhibit a pristine incarnation of such scattering
rods. This provides a physical picture for their appearance, elucidates the
role played by monopole excitations and identifies conditions conducive to
their observation.
