It seems time crystals are real. They were first proposed in 2012 by American theoretical physicist Frank Wilczek and are a phase of matter that exists only at tiny atomic scales and extremely low temperatures (-459.67 degrees Fahrenheit, just one-ten-thousandth of a degree above absolute zero). These crystals don't look like natural crystals but the term is used to describe their regular changes in quantum states over a period of time. Their oscillation between two low-energy states, in theory, could be continuous and be a true type of perpetual motion.
Not quite the same as the Klingon time crystals, but this research was probably the inspiration for the fictional ones.
Not quite the same as the Klingon time crystals, but this research was probably the inspiration for the fictional ones.