The Muschelkalk is famous for its well preserved lobsters. Like the glypheid genera Pseudopemphix, Aspidogaster, and Litogaster, and the nephropid Lissocardia, the spiny lobster Pemphix has a calcified carapace and is commonly preserved as exuviae. Other than these, actively swimming penaeid shrimps are extremely rare. This is also the case with marine sea slaters (Isopoda), horseshoe crabs (Limulida) and the extinct sea helmets (Cyclida). In contrast, the small shell-bearing conchostracans and ostracods occur abundantly on certain bedding planes. Conchostracans, which are distantly related to water fleas, have a bivalved carapace. The minute ostracods have two calcified valves, which enclose the entire body.
Pemphix sueuri inhabited burrows built within semi-consolidated sediment in the seafloor as a scavenger. Pemphix is the biggest and most common Muschelkalk lobster.
Lissocardia silesiaca (Nephropidae) had long, slender pincers that suggest highly specialized food gathering. Its burrows are preserved as Pholeus trace fossils. Lissocardia was originally described from Silesia, but during the last years, excellent specimens were collected in the Upper Muschelkalk of Central Germany.
Pseudopemphix albertii (Erymidae) occurs in the lower parts of the Upper Muschelkalk. Its anterior pair of legs bears powerful pincers. Its branching burrows are typical thalassinoid trace fossils. The figured cephalothorax was collected in the Trochitenkalk Formation of the Crailsheim area.
Until now, only two isopods have been found in the Muschelkalk. The less than half a centimetre long specimen from the Upper Muschelkalk of Hohenlohe was assigned to the suborder Cymothoidea.
Ostracods are indicators of environmental conditions and may also be good index fossils. Some ostracods like the unidentified Lower Muschelkalk species (above) were marine, others, like the genus Glorianella (below) from the ‘Ostrakodenton‘ near the top of the Upper Muschelkalk indicate brackish water.
Conchostracans inhabited the Muschelkalk Sea when the water was brackish. Hence, their bivalved carapaces are only found in a few marlstone horizons indicating freshwater incursions. In contrast, many Lower Keuper bedding planes are densely covered with their shells. The picture shows Palaeestheria minuta.