Researchers at the Pierre Auger Observatory in Argentina have measured the longitudinal and lateral distributions of ultra-high-energy cosmic-ray air showers with primary energies of 6–16 EeV (corresponding to centre-of-mass energies of 110–170 TeV). The average shower is 1.33±0.16 and 1.61±0.21 times larger than predicted from the leading LHC-tuned models EPOS-LHC and QGSJetII-04, respectively, corresponding to an excess of muons. This suggests either flaws in the underlying models or a more fundamental change in physics at these energies.