Even if you move it with a pencil it goes back to its original shape
In: 6
The surface tension answer is correct, but I feel like it just pushes the question back to “where does surface tension come from”.
Water is *cohesive* – i.e., water molecules like to stick to other water molecules, more than they want to stick to e.g. your pencil. There is an attractive force pulling the water molecules together into a blob and *holding* them together. This force is really the [electrostatic force](https://en.wikipedia.org/wiki/Coulomb%27s_law), the same “opposites attract” force between protons and electrons. Water molecules are shaped in such a way that the electrons mostly bunch up on one side of the molecule, leaving the molecule with a positive side and a negative side. Then in your water droplet the water molecules all orient themselves so that the negative side of one molecule is being tugged on by the positive side of another one.
A sphere has the least surface area for any given volume, and therefore, for the water droplet, the least interaction with other things that aren’t other water molecules.
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