I stole the title of this post from the discussion thread at the mildlyinteresting subreddit, where I encountered this photo [croppped by me for emphasis] of headphones that had been dropped in sand with high iron content. Two comments from the thread:
"I grind metal at work and its super annoying. I have to wipe the metal off meticulously after every shift or else it starts to stain the airpod case."
Iron sand beaches are fairly common around the world. The ones I've been to have fine grain like a regular beach but it's a lot darker because of the iron mixed in. They get ridiculously hot on a sunny day - as in they will burn your feet if you stand still for more than half a second