Back in the day, when I was at Fermilab, there had been a number of people who continued to speculate and predict the existence of a strange sort of particle, that could be formed from 5 quarks. Now, I use the word strange because in our lives, we only see two types of particles formed from combinations of quarks.
All particle made of quarks are referred to as hadrons. But there are then two main types of hadrons: mesons and baryons. Mesons are combinations of two quarks (a quark-anitquark pair), and baryons are made form three quarks. The quarks are held together by the strong nuclear force. You are made from electrons and baryons, better known as the proton (two up quarks and one down quark) and the neutron (two down quarks and one up quark), for instance.
No one has ever had confirmation of different combinations of quarks, until now. Check out the actual article published from CERN. Keep in mind that pentaquark particles are allowed and have been predicted for decades from the Standard Model, the main theory explaining all we know about particles and the forces between particles.