Head and body length is 150-220 mm and tail length is 15-16 mm. Weights in the wild have been recorded between 180 and 270 gms. The entire upper portion of S. setosus is covered with sharp, bristly white-tipped spines that even cover the small tail projection. The muzzle, limbs and underside are covered with soft, scanty hair, and are buffy, dark brown, or whitish. The white-tipped spines on the upper parts of the body create a mottled effect, with underlying colors ranging from comparatively pale to black. The hind limbs are slightly longer than the forelimbs, and all digits are well developed. Females have five pair of mammae.

S. setosus favors dry forests and agricultural areas. It is believed to be strictly nocturnal. The nest is leaf-line, with a short tunnel leading to the entrance. While the animal may be active throughout the year, it is capable of torpor, spending most of the winter in a restricted foraging area. When threatened, the hedgehog curls into a ball, exposing its sharp spines in every direction. It is a good, but slow, climber. The diet of S. setosus consists of earthworms, grasshoppers, and carrion.

Adults are primarily solitary, occasionally associating during mating season. Gestation is variable, depending on the ambient temperature. Average gestation ranges from 51-61 days in captivity, and is shorter when the temperature is high. Average litter size is 3 young.

They are found in all latitudes and phytographic zones: eastern humid forest, central highlands, northern highlands, sambirano, western deciduous forest, and spiny bush in Madagascar.