Quark Bound States (IMAGE) Forschungszentrum Juelich Caption For a long time, physicists were only able to reliably verify two different classes of hadrons: baryons and mesons. Experiments performed at Jülich's accelerator COSY have now shown that, in fact, another class of exotic particles made up of six quarks exists. Credit Source: Forschungszentrum Jülich/SeitenPlan (<a target="_blank"href="http://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a>) Usage Restrictions <a target="_blank"href="http://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a> License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.