Nautllus macromphalus, a species of chambered nautilus, found by Timothy Swan on Marion Bay Beach, 24 March 2021. The species lives in the Coral Sea. The most recent compartment (chamber) has broken off the shell, so it's clear that there was no living animal present when the shell beached. More likely the empty shell, being buoyant, had travelled without its occupant down the EAC all the way to Tasmania.