Your appendix stores samples of good bacteria so it can repopulate your digestive system in case they are wiped out entirely by diseases such as diarrhea. – WTF Fun Facts
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5011360/
digestive system
WTF Fun Fact – Stomachless Horse
Seahorses don’t have stomachs, just intestines for the absorption of nutrients from food. As such, food passes through their digestive system rapidly and they must eat almost constantly. – WTF Fun Facts