There are many known -- you might call them "small" -- normal elementary particles. (In contrast, the Ball-of-Light Particle Model predicts that there are many unknown "large" elementary particles.) Some of these particles are stable -- that is, harmonic -- such as: electrons and protons. Some are not stable -- that is, they are nonharmonic -- such as: muons or neutrons. (See also, the Weak Force.)
The decay of normal matter or other "small" elementary particles would be the "sixth energy level" in a series of energy levels that have a harmonic pattern.
The Ball-of-Light Particle Model predicts that there is no limit to the maximum size of an "elementary particle" other than all of the energy in the universe! This prediction is a result of the replacement of Relativity by the Speed-of-Light Definition of Time and the Grand Unification Theory called the Ball-of-Light Particle Model. With Relativity, there is a maximum size to an object of about 80-100 solar masses before it collapses in a Black Hole.
Some objects that might be classified as "large" elementary particles include: