While crocodiles have the strongest stomach acid (comprised of hydrochloric acid and peptic proteolysis) of any creature alive on the planet today, something as small as a wooden toothpick swallowed by an adult croc can penetrate the animal's stomach wall causing lesions, damage to internal organs, peritonitis, and can even cause cirrhosis of the liver. Larger gastric foreign objects, even when otherwise edible such as bird wings, have caused stomach distension in crocs resulting in death. As for foreign objects “passing on through,” crocodiles actually have an extremely small pyloric opening into the duodenum which prevents the escape of accidentally ingested objects, such as the trash in this photo; thus, the animal dies of gastric blockage. Although crocs do regurgitate tiny hair balls (yes, like cats and owls), it seems they are unable to regurgitate larger unwanted non food items due to their anatomy. For many reasons, a fed croc is a dead croc.