A Flash in the Dark: The Mystery of "Phoebe"
On 18 December 2019, a star in the Large Magellanic Cloud brightened symmetrically for about one hour, then returned to normal.
The phenomenon, named Phoebe, was identified as a gravitational microlensing event by a team from Swinburne University.
A Lunar-Sized Lens
The lensing object's mass was calculated at approximately three times that of the Moon. This is too small for a stellar black hole (minimum ~5 solar masses) and too small for most planets.
The leading hypothesis is a primordial black hole formed in the early universe.
A Dark Matter Candidate
Statistical analysis indicated Phoebe is 100,000 times more likely to be a dark matter object than one associated with normal stellar matter.
If confirmed, it would be among the oldest detected objects, dating from the Big Bang, and the first evidence of a primordial black hole.
Source
The findings are from the AMPM II survey, published discussing a lunar-mass microlensing candidate in the Milky Way halo.