Kutorginides typically have a ventribiconvex shell (both valves convex, the ventral valve moreso) and a strophic (straight) hinge line. Based on fossils of
Nisusia, the shell’s internal (secondary) layer appears to have a microstructure of
calcite fibers. Several kutorginides are preserved in
lagerstätten, elaborating on the structure and location of the pedicle relative to the two posterior openings.
Kutorgina chengjiangensis, from the
Chengjiang Lagerstätte of China, has a pedicle in the form of a thick annulated stalk. Despite its thickness, the pedicle is joined to the shell at the pseudodeltidium, strongly suggesting that it was originally derived from within the small pedicle foramen. The large posterior opening probably helped support strong diductor muscles in this interpretation. Each fossil includes a distinctive
silicified tube within the large posterior opening. This tube has long been interpreted as a
coprolite, suggesting that kutorginides had a complete gut terminating at a gap in the rear of the shell. This condition is otherwise unknown in articulate brachiopods, and is more akin to
inarticulates in the subphylum
Craniiformea. However, modern brachiopods have very small fecal pellets, so the silicified tube may be better interpreted as an adult pedicle. The smaller foramen at the tip of the pseudodeltidium may be a remnant of a larval pedicle, later rendered redundant by a second pedicle developing at the hinge in adulthood. In this scenario, the pedicle of other rhynchonelliforms would be homologous to the larval pedicle of
Nisusia sulcata. ==Subgroups==