The scorpion, a venomous arachnid of dry country whose sting can kill, was met in the ancient world with a mixture of fear and reverence. In Egypt it was embodied in the goddess Serqet or Selket, shown with a scorpion on her head, a protector of the dead who guarded one of the four canopic shrines, and paradoxically a guardian against the very venom she personified. The myth of Isis tells how the goddess, hiding with the infant Horus in the marshes, was escorted and protected by seven scorpions, and how the sting of one, meant for Isis, struck a child instead and was healed by her magic, the scorpion as both danger and, mastered, defence.
A genuinely strange fact about the living animal now underlies part of its old reputation for uncanny power: scorpions fluoresce a vivid blue-green under ultraviolet light, a property of a thin layer in their exoskeleton discovered by researchers only in the twentieth century and still not fully explained, since the effect works even in scorpions blind from birth. Modern medicine has in turn found real use for scorpion venom: a compound called chlorotoxin, isolated from the deathstalker scorpion, is being developed as a tumour-marking agent that binds selectively to certain brain cancers, an active area of clinical research rather than a folk remedy.