A major breakthrough! A team led by professor Guo Junfeng from Chang'an University has unearthed the world's earliest known fossil of a true coleoid cephalopod, the Eoceras shaanxiense, from Cambrian strata in Zhenba, southern Shaanxi. The fossil measures only a few millimeters in size, with a shell resembling a small straight cone, but its internal structure is remarkable: it already possesses a siphuncle: the tubular structure connecting the body chamber to the apex and subdivided by septa into gasfilled chambers. In simple terms, this is the earliest known "buoyancy control device" for cephalopods. Previously, the earliest universally recognized cephalopod was Plectronoceras from the Late Cambrian (around 490 million years ago); this new find pushes the direct fossil evidence back by approximately 30 million years. The research team also noted that the discovery offers entirely fresh perspectives for reinterpreting enigmatic tubular fossils from the Cambrian explosion.