Nisusia was a lampshell with a bivalve (two-part), calcareous  shell enclosing most of its body. It often lived a sedentary life, attached by its pedicle (foot) on the seafloor. This enabled Nisusia to reach up higher from the sea bed, and reduced the risk of mud and waste products entering between the two sides of the shell. Nisusia may also have been able to make use of the water currents generated by the sponge, to filter out its own food.