Halkieriid
Halkieriid refers to an extinct group of marine animals that lived during the Cambrian period. These creatures are known primarily from fossil evidence, particularly from Lagerstätten deposits which preserve soft tissues. Halkieriids are characterized by their elongated, slug-like bodies, typically ranging from a few centimeters to over 30 centimeters in length. They possessed a distinctive shell-like structure, often referred to as a sclerite, which covered parts of their body. These sclerites could be numerous and arranged in rows, or they might have been concentrated in specific areas.
One of the most remarkable features of halkieriids is the presence of a complex shell or cap
The internal anatomy of halkieriids, as revealed by exceptionally preserved fossils, indicates a relatively simple body