The second unit is a 3.7 (Engis) to 4 m-thick (La Mallieue) coral biostrome sensu stricto. The rugose coral colonies are laminar, discoid, of various sizes, from a few centimetres to 70-80 cm in diameter (and possibly more).
The density of the frame builder can reach 90% of the rock; the matrix is a shale or a slightly argillaceous packstone more or less dolomitized.