Particles with any (rest) mass can have lots of things that happen inside. https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structu

Particles with any (rest) mass can have lots of things that happen inside. https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/ https://profmattstrassler.com/articles-and-posts/particle-ph...