A re-examination of a particle discovered in 2015 has scientists debating its true identity. A recent analysis by the LHCb collaboration at CERN raises questions about the identity of this pentaquark—and may have taken scientists back to square one in the search for a particle that could shed light on questions about color.

During the last four years, LHC scientists have filled in gaps in our knowledge and tested the boundaries of the Standard Model. Since the start of Run II in March 2015, they’ve recorded an incredible amount of data —five times more than the LHC produced in Run I. The accelerator produced approximately 16 million billion proton-proton collisions — about one collision for every ant currently living on Earth.