Strangelets, and specifically nuclearites, their heavy species, are very dense, compact and potentially fast objects made of large and roughly equal numbers of up, down and strange quarks, which may inhabit the universe. Their existence was first hypothesized by Edward Witten back in 1984. These objects have never been detected before and have so far attracted less attention than meteors, perhaps due to their lack of relevance in particle physics.
Click here for original story, Study sets limits on the flux of heavy compact objects using data from the Pi of the Sky project
Source: Phys.org