Tsathoggua's will is carried out by the "formless spawn", entities made of black ichor. They are extremely resilient and very difficult to dispatch. Formless spawn can take any shape and can attack their targets in nearly every conceivable way. They are surprisingly flexible and plastic-like, and can quickly flow into a room through the tiniest of cracks. They attack by trampling their targets, biting them, or crushing them with their grasp. The "Call of Cthulhu" roleplaying game's entry on Formless Spawn also claims that they are powerfully acidic in substance and can dissolve human flesh with even a slight touch.