States of matter
The protons and neutrons that make up atoms are made of even smaller things called quarks (which are "glued" together by things called "gluons"). At incredibly high temperatures over 2 trillion Kelvin, quarks and gluons turn into another state of matter. Humans can make a little bit of quark-gluon plasma in the Large Hadron Collider at CERN, but it doesn't last long before cooling down.