Quark

A quark is the subcomponent of a Subatomic particle and is comprised of preons. Quarks combine to form larger particles called hadrons, the most stable of which are the subatomic particles. They are the only Tier 2 particles to experience all 4 forces creatable in our Universe (magnetism, gravity, weak nuclear, and strong nuclear force).

Types
There are 6 types of quark: up, down, charm, bottom, top, and strange. The heaviest quarks are the smalleest, making quarks very dense. The strange quarks may create strange matter which can infest baryonic matter.

Quark Star
Main article: Quark Star

Quarks may create dense quark stars after the death of regular stars, but this is hypothetical and the only time we spotted a Tier-2-based star is neutron stars.