Remember that scene near the end of Star Wars: The Last Jedi when an entrenched Resistance fighter dips his hand onto the surface of Crait, licks his finger, spits, and says, "Salt"? Yeah, kinda hard to forget a strange scene like that, especially since Rogue One director Gareth Edwards (in a small cameo role) gives the dude a confused look.
Upon first glance, it seems like a way in which writer/director Rian Johnson opted to exposit that we're now on a mineral rich planet and that the wide white plains of Crait are salt flats like those you'd find in western Utah. However, a geophysicist by the name of Mika McKinnon has dug deeper into the significance of the action, explaining the practice of licking rocks, which is apparently a common practice among those who study the composition of the Earth for a living.
"I’m feeling weirdly hurt by the viral tweet mocking geoscientists for licking rocks," she wrote on Twitter. "I get that we’re a bit weird even for scientists and get a bit more blunt with our toolset, but licking rocks is a real strategy. Taste & texture are diagnostic ... You don’t NEED to lick rocks; it’s just faster & easier."
When it came to The Last Jedi, McKinnon posited that not only was it not weird, it was a totally believable moment "bordering on geo fan service ... And it’s tactically important to know what rocks encompass you unless you’re a fan of dumb ways to die."
As it so happens, the salt-licking scene has also turned into an Internet meme, meant to represent the toxic (or salty, if you will) segment of the Star Wars fandom, which has, to date, nearly driven Ahmed Best (Jar Jar Binks) to suicide, demanded a remake of The Last Jedi, and forced Kelly Marie Tran off of social media.