If you remember correctly you will have noticed that your cereal didn’t spread randomly over the surface of the milk(or alternate fluid). You will have noticed that they clump together, kind of like a soggy hug for inanimate objects.
This is a mysterious phenomenon known as the Cheerios Effect.
This kind of gathering together happens with everything that floats, from paperclips to bubbles. It was named after the eponymous cereal as it is particularly subject to this effect. This mysterious clumping works because Cheerios, or your preferred cereal of choice, disrupt the cohesive forces between the surface molecules. Also the individual pieces of cereal create little dips or depressions in the surface of the water which causes them to move together. Cool eh?
One more thing to consider is this; gravity is just a depression in space-time, when you get lots of objects in space creating all of their little depressions they become attracted to each other. This is how galaxies form, in almost exactly the same ways as cereal clumps together. Think about that the next time you are picking at your cereal, you are almost watching a new galaxy forming. Although you may want a few more Cheerios to create a 1 : 1 scale model of the milky way.