Sand boas are built around one behaviour. The body is short and heavy, the tail blunt, and the head barely distinct from the neck. The snout is reinforced and wedge-shaped for pushing into loose substrate, and the lower jaw sits recessed within the upper so that the mouth line does not scoop sand while the snake burrows.
The eyes are the giveaway. Rather than sitting on the sides of the head as in most snakes, they are placed high and directed upwards, so the animal can watch the surface with the rest of the body concealed. A hunting sand boa lies buried under a few centimetres of sand, strikes upward at a passing rodent or lizard, drags it under, and constricts it below the surface.
Burial serves thermoregulation as well as ambush. Sand a short distance down is markedly cooler than the exposed surface during the day and holds warmth after dark, so the same behaviour that hides the snake also buffers it against the extremes of a semi-desert climate.