Perhaps you've noticed as you get down to those last few spoonfuls of breakfast cereal, the remaining bits tend to cluster around each other in the middle of the milk or hang on around the sides of the bowl. Why is that?
Scientists have asked the same thing, measuring directly for the first time what has been dubbed the "Cheerios Effect".
Writing in Physical Review Letters, the Brown University researchers say it's a mixture of gravity and surface tension, with the Os drawn to each other since they're not heavy enough to sink.
The findings go further than your bleary-eyed morning ponderings. Eventually, the data could be used to help design microscale machines and robots for tasks like environmental monitoring.