It is fairly well known that Hermes was sometimes represented by “herms”, sculptures in which the torso was simply a cuboid, with only the bust and a phallus differentiated from the abstract shape. (These herms could also represent other deities, or humans.)
Less well known are a different kind of herm, also known as hérmaios lóphos (‘Hermaean ridge’) or hérmakes (sg. hérmax), which consisted of heaps of stones piled up along roads, especially crossroads. As Theophrastus describes, especially pious people would anoint these with oil and kneel down before them in worship when they passed by one. Here are some primary sources discussing such hermax piles; more may be added in the future.
2 Hesychius ε 5939
“Hermaean ridge”: the heaps of stones, herms, which are on the roads in honor of the god; for (Hermes) is Enodios (‘on/of the road’).
3 Scholia on Nicander, Theriaca 150
Hérmakes are the Hermaean and rocky places; or Hermac stones heaped up in honor of Hermes. In more recent usage, they are (called?) hérmata.
Hérmakes are stones heaped up as images (or ‘in the shape’?) of herms; for they used to call masons herm-sculptors, stones with a shape herms (hermai), and unhewn stones hérmakes.