The Hammerhead is an armoured grazing herbivore with a hardened head shield. It is non-aggressive by default, but unlike most herbivores it is territorial: enter the herd’s space and it will ram you with that shield. It travels in herds and is related to the Epicurean (which lacks the head shield).
Counterplay is mostly about respect: give the herd room and it ignores you entirely. Scanning a Hammerhead unlocks a biomod, so the goal is usually to approach the edge of a herd carefully, scan, and back out without triggering a charge.