Evenly spaced, symmetrical, dike-like protrusions 3 to 5 inches long of white-weathering limestone occur within a Permian medium-bedded micrite unit. These protrusions project upward into grey-weathering limestone beds. Along bedding planes the structure displays a polygonal pattern. Injection of fluid lime mud into overlying, partly lithified lime mud formed the structure. An incipient mud crack pattern in the overlying lime mud controlled the lateral distribution of the dike-like protrusions.