One of the many things that My Octopus Teacher gave me to ponder was this very basic fact about crustacean locomotion.
I was born in Massachusetts. I've spent part of the summer in Maine for the last decade+. I've been eating lobster my whole life and until this week I had NO IDEA that lobsters swim...backwards? Like it's always been obvious that their giant tail is a flipper, but I never really gave any thought to how it would practically be used to propel them in their natural environment. I've only ever seen them alive in cramped tanks or in paper bags sitting in the sink waiting to be steamed so to the extent I've seen them move with my own eyes they've been walking or crawling, slowly. But in the sea these things can really book it and they do so by moving ass-first like a car in reverse with their claws trailing. It's a small thing but that is so wild to me.