Primordial black holes are a dark matter candidate.
Suppose you put a primordial black hole the mass of an asteroid in Earth's core. Will it grow? NO! The black hole will be on the order of a proton in size. At this scale, Hawking radiation is so powerful that particles will be repelled by the BH. When the BH finally explodes, the energy released in the final few seconds is about a 7.0-8.0 earthquake (we are so far from the core that we wouldn't feel much). A large enough BH would be able to grow, but the process emits so much energy (~10% of in-falling mass) that Earth would become a ball of white-hot plasma before much mass was consumed.
But what happens in a denser medium? In white dwarfs and neutron stars, this paper stated that a single hole would rapidly consume it's host (without giving any justification):
Is this claim valid? Has any paper examined the physics of a tiny BH devouring it's host and calculated an (approximate) formula on when the hole would begin to grow as a function of the star's central density and black hole mass? And whether this would happen fast enough to destroy the star in 10^9 yr time scales?