Kollodidisissa

Kollodidisissa is a genus of extinct marine arthropods belonging to the order Agnostida. These small trilobites are known for their diminutive size, typically measuring less than 10 millimeters in length. They are characterized by their highly reduced, often featureless cephalon (head shield) and pygidium (tail shield), which are remarkably similar in shape and size. This characteristic, known as holopygial effacement, is a defining feature of many agnostid trilobites.

Fossils of Kollodidisissa are found in Cambrian and Ordovician marine sedimentary rocks worldwide, indicating a wide geographic distribution during these periods. Their precise ecological role is not fully understood, but like many agnostids, they are thought to have been planktonic or nektonic, drifting or swimming in the water column. Their small size and lack of prominent features suggest a specialized lifestyle, possibly involving filter-feeding or scavenging. The study of Kollodidisissa contributes to our understanding of early arthropod evolution and the paleogeography of ancient oceans.