Labyrintichnus terrerensis Uchman et Álvaro, 2000

Description. L. terrerensis consists of slightly curved tunnels, which may branch off with an acute or right angle. In some places, a master tunnel is visible or a radiating plan results from branching. Blind appendages and intersections are common. At branching points, the tunnels nels are commonly enlarged. The fill of the horizontal burrow parts is mostly without structure and strongly compacted. It consists of blue-grey pyritic marlstone and contrasts to the light grey to ochre colour of the micrite. No lining has been observed, however, irregular boundaries may occur locally. Some deeper parts of the burrow system are lined with one or two vague rows of faecal pellets (Coprulus oblongus), of which some accumulate sulphide minerals. The burrow density is relatively high, and total width varies from 1–7 mm with a downward decreasing size.