So, time crystals. They cropped up in the news a couple months ago, and I'm just now getting around to talking about them. Despite their horrendous name - implying that they might have something to do with healing powers, energy fields, talking to your deceased relatives, or who knows what nonsense - they're perfectly reasonable physics objects.
A "normal" crystal is a pattern that repeats in space. A time crystal is a pattern that repeats in time. While we have lots of things that repeat in time (e.g., clocks), what makes time crystals special is that they do it in the minimum-energy state of the system, meaning they could do it forever.
While that sounds like some sort of perpetual motion device, it's impossible to pull energy out of the system, so don't expect these to power your smartphones anytime soon. Still, that didn't stop some press outlets from writing all-caps headlines about time crystals rewriting known physics, revolutionizing our understanding of time, or even shining a light on dark energy.
The verdict: time crystals are interesting. But that's it.