These extraordinary-looking creatures are man-sized, with a powerful human torso and two arms ending in very sharp claws. Supported on the thin (but very strong) neck is the creature's head which is a skull - usually of an animal but sometimes of primitive man. The lower part of the creature's body consists of a cylinder of muscle and skin which can be compressed spring-style and released, below which are three long and thin single-toed feet. Its manner of locomotion -since it lacks legs as such - is a series of springs;""
Don Turnbull ed., Fiend Folio