It is hard to visualize over 1000 nodes and 2000 edges like shown at the above snapshot. It is named as Hairball because its congested structure. I obtained that graph from PPI network of Plasmodium_falciparum_3D7 published with the article PubmedID:16267556. Mainly, it is hard to see anything from the visualization. We can only infer that there are highly connected structures inside hairball.
What will happen when grab from the heart technique. Let's see:
We randomly select some nodes and grab from the graph. The resulting graph stays with less than 1000 nodes and edges. Then let's see what happened to level-1 grabbed part:
Here, there are less than 500 nodes and at least three times number of edges. This is also another hairball. Next let's grab another heart from the hairball and see:
The resulting graph is sparse and nodes/edges are clearly visible. Then we should check level-2 grabbed part:
It is again hairball :). Still can not understand the pattern, nodes and edges. Let's continue with level-3 heart then:
Edges/Nodes number are getting less. What about level-3 heart then:
Now it is not insane graph. Complicated but not like hairball.
What I understand from this post, hairball can be visualized in such pattern. Level-by-level visualizations from top to deepest level by grabbing from heart technique.