Elasmosaurs loved their gastroliths – round, polished stomach stones – have been found amid their bones. These stones would have been swallowed to help grind down their catch and lower their natural buoyancy. Surprisingly elasmosaurs displayed a remarkable discernment in their selection of pebbles. The Puntledge elasmosaur from Courtenay, British Columbia, for example, had a yen extrusive volcanic rock. When the fossilized skeleton was excavated, every last one of the stones in its abdominal cavity were basalt.