The structure is calcium ions.
Water had the capability to hold up the thin overhang of the underground.
When water is depleted, there is nothing to support this overhang, which eventually led to the formation of sinkholes.
As for the collective behavior, it's all because of the scarcity. Water is one of human's basic needs to survive. When water is scarce, this will force the people to compete with one another to obtain it, which will cause the behavior
We do science because if we didn't we would not know a lot of the things we do know now.
What are "these" cells you are referring to?
