 Even if there were only a few strange stars initially, violent events such as collisions would soon create many fragments of strange matter flying around the universe.Because collision with a single strangelet would convert a neutron star to strange matter, all but a few of the most recently formed neutron stars should by now have already been converted to strange matter.This argument is still debated, but if it is correct then showing that one old neutron star has a conventional nuclear matter crust would disprove the strange matter hypothesis.