Scientists using the Large Hadron Collider have identified a form of particle that until now was only theoretical. Dubbed Xi-cc++, it’s the first double heavy particle, something that might help reveal more about how atoms hold together.

The BBC explains that every particle is made up of quarks, each of which is of a particular type that can be categorized as either light or heavy. To date, no particle has been detected that has more than one heavy quark.

Xi-cc++ has two heavy and one light quark. Not only is it the first time that such a particle has been observed, but the behaviour of the quarks is something that’s not been seen before.

Normally in a particle with three quarks, the quarks would move around one another in what Oxford University’s Professor Guy Wilkinson describes as “an elaborate dance.” With Xi-cc++, the movement is more fixed: the two heavy quarks orbit one another while the light quark orbits around the pair, effectively treating the two heavy quarks as a single system.

Researchers at CERN hope further measurement and analysis of Xi-cc++ will uncover more insight into how quarks stay together in particles.