Holeums are hypothetical stable, quantized gravitational bound states of primordial or micro black holes proposed by physicists in 2002.
From an interesting discussion happening on the Delta Green Mailing List:
It’s a possibility, though slim, of having matter made up of stable, micro black holes. These wouldn’t have anymore mass (thus gravity) of the same amount of regular matter. A person, made from Holeum, would weigh the same as a person made up of normal (baryonic) matter. In fact under normal circumstances one of these “people” could be standing next to you right now and neither of you would know it. You would only, under normal circumstances, interact gravitationally.
The discussions go on positing that horrors from beyond could conceivably by made of Holeums, talks about a naked singularity, then there is a nice bit about the end of the known universe.
If you want to read more about the physics behind this discussion start with this Wikipedia article, there are more included in the Yahoo group.