In common usage, the difference between Hoodoos and pinnacles or spires is that hoodoos have a variable thickness often described as having a "totem pole-shaped body". A spire, on the other hand, has a smoother profile or uniform thickness that tapers from the ground upward. At Bryce Canyon, hoodoos range in size from that of an average human to heights exceeding a 10-story building. Formed in sedimentary rock, hoodoo shapes are affected by the erosional patterns of alternating hard and softer rock layers.