Halkieria evangelista Conway Morris and Peel 1995 from the Lower Cambrian Sirius Passet lagerstatte.

Morphology:

Body elongate, dorsoventrally flattened, with a larger shell plate in either end. The remaining dorsal surface is covered by sclerites arranged in three morphologic zones, termed the palmate, cultrate and siculate zone. The ventral surface was naked. The sclerites were aragonitic in mineralogy whereas the shell plates remain uncertain.

Systematic position:

Crown group mollusc, stem group aculiferan.   

Picture: scale in mm. Courtesy of Jakob Vinther.