Up quarks have a +2/3 charge, and down quarks have a -1/3 charge. If you add and subtract those fractions, you get the +1 charge of a proton. Valence quarks get lots of attention.

As quarks rain down on the earth, the British scientists suggest in their Nature article, those with a negative charge combine with oxygen in the ocean to form fractionally charged quark-oxygen atoms.

This process, called fragmentation, gives physicists clues about how quarks behave when they’re released from the tight grip of the strong nuclear force. Now here’s where the symmetry jumps in.