pygidia
The pygidium is the posterior-most part of an arthropod's body, formed by the fusion of abdominal segments. It is typically found at the very end of the abdomen. The shape and size of the pygidium can vary greatly among different arthropod groups, and it often serves important functions.
In crustaceans, such as trilobites (which are now extinct), the pygidium was a prominent feature. In many
The pygidium can have various appendages or structures, depending on the species. For instance, it may bear