We live in a cyclic universe of a sort because every few years somebody tries to resurrect the idea that dark matter is somehow related to primordial black holes, i.e. black holes formed in the very early stages of the history of the Universe so that they have masses much smaller than black holes formed more recently by the collapse of stars or the merger of other black holes. If it forms very early the mass of a PBH could in principle be very small, much less than a star or a planet. The problem with very small black holes is that they evaporate very quickly via Hawking Radiation so would not survive the 14 billion years or so needed to still be in existence today and able to be dark matter.
An idea that was used in the past to circumvent this issue was that something might stop Hawking Radiation proceeding to reduce the mass of a PBH to zero, leaving a relic of finite mass usually taken to be the Planck mass. The suggestion has returned in different (but still speculative) guise recently, fueling a number of media articles of varying degrees of comprehensibility, e.g. here. The technical papers on which these articles are based can be found here and here.
Fortunately, there is now one of those excellent Cosmology Talks explaining the latest idea of how Hawking Radiation might break down and what the consequences are for Primordial Black Holes as a form of Dark Matter.
