Strangelet

A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. Its size would be a minimum of a few femtometers across (with the mass of a light nucleus). Once the size becomes macroscopic (on the order of metres across), such an object is usually called a quark star or "strange star" rather than a strangelet. An equivalent description is that a strangelet is a small fragment of strange matter. The term "strangelet" originates with E. Farhi and R. Jaffe. Strangelets have been suggested as a dark matter candidate.

Read more about Strangelet:  Natural or Artificial Occurrence, Dangers, Debate About The Strange Matter Hypothesis, In Fiction