Undetermined porifera

Towards the end of the Jurassic, about 155 million years ago, a warm, shallow sea, dotted with islands, covered much of what is now Germany. Sponges and corals grew on the elevations of this sea, forming reefs that divided parts of it into isolated lagoons. Within these warm, isolated lagoons, salinity increased and the water could be anoxic or even toxic at various intervals. Apart from cyanobacteria and small protists such as foraminifera, nothing could survive for long in the deep waters of lagoons. However, any organism that fell was buried in soft carbonate mud. In this way, many delicate creatures were not consumed by scavengers or destroyed by currents.

Today, these carbonate muds form a type of fine-grained, flat-cleavage limestone, known as Solnhofen limestone, famous for its fossils. Although relatively rare, fossils from the Solnhofen Limestone can show organisms in great detail and often include fragile or soft-bodied organisms that typically leave no fossils, or only fragments.