Personal biodiversity. Each of us is an ecosystem unique to itself.
Some fragments of navel DNA precisely match the DNA of a known species of bacteria. In other cases, they’re close enough to a species for Hulcr and Lucky to assign them to a genus, a family, a class, or some higher unit of classification. In a few cases, the bacterial DNA is so exotic that all they can say for sure at this point is that it is bacteria.
Hulcr, Lucky, and Dunn had lots of questions about the things that dwell in the human omphalos. Are they different from the species that live in other parts of the skin? Do they differ from one person to the next? Is there a core set of species found in all navels? To address these kinds of questions, they tallied up the number of volunteers who carried each species, and investigated how each species makes a living.