Spherule comes from the Greek word “sphaira” for sphere. Cosmic spherules are solid, rounded particles ranging from micrometer to millimeter in size with distinct chemical compositions indicating their extraterrestrial origin. Cosmic spherules are predominantly found in ocean floor deposits on Earth and are mainly produced by frictional heating, melting, and ablation of meteoroids upon atmospheric entry. Solidified impact-induced molten droplets of meteoroid and target materials are less abundant on Earth but would predominate on the exposed surfaces of atmosphere-less bodies like the Moon that were strongly gardened by impacting meteoroids in their early history.