Emended diagnosis: irregular, basically net-like burrows in sediment fill of shells, visible on the surface of internal moulds. The size of the whole structure may vary from microns to centimetres. The networks may continue laterally as ramifying, simply branching and, less commonly, also looping burrows (emended af ter Bertling 1992).
Diagnosis: Irregular elongate and net-like burrows in sediment fills of shells. Visible on the surface of internal moulds. The size of the meshwork may vary from microns to centimetres, depending on the shell-bearing and the burrowing biota involved.