  Recent CMS observations in the di-$J/\psi$ invariant mass spectrum reveal new
structures at 6638 MeV ($X(6600)$)) and 7134 MeV, and confirm the $X(6900)$ at
6847 MeV. These findings provide crucial insights into four-charm-quark matter.
The CMS Collaboration's result serves as a testament to the progress in
exploring exotic hadronic matter.
