In February 2023, a cosmic particle detector housed deep in the Mediterranean Sea recorded the arrival of a neutrino with approximately 20 to 30 times more energy than any other neutrino documented previously. Labelled KM3-230213A, the particle had a calculated energy of 220 petaelectronvolts (PeV), far greater than the 10 PeV of the previously most energetic neutrino. Just as a rock cannot describe the nature of a mountain, a 220 PeV neutrino alone isn’t useful in explaining the phenomenon that gave rise to it. Different branches of science use and study neutrinos for different reasons. Because neutrinos travel through the universe without being deflected or absorbed, they can provide valuable information about very distant cosmic events.