Diagnosis: Ramified burrows on the surface of internal moulds with an oval crosssection which increases slowly in diameter by a factor of 5 to 10, approximately. At ramifications, the bent main burrow is not reduced in size. Lateral burrows mostly have a smaller diameter. Polygonal areas on the surface of internal moulds may be produced by the unification of ramified burrows.
Description: The burrows are best visible on the surface of internal moulds and may either be empty or filled by sparite. The diameter is 30~t to 5011 in the earliest visible stages and gradually increases up to 15011. Because the traces are not confined to the surface of internal moulds they sometimes appear to be constricted or even terminated, depending on the angle of descent from the surface.