When we are in cook the meat, we can see the liquid fat of animals floating on the broth. When the broth is completely cooled, it will solidify into solid fat.

When drinking soup, we can also see the floating oil droplets in the bowl.

Data expansion:

Water is a polar liquid, while edible oil is a nonpolar liquid. They can't mix. Moreover, the density of oil is smaller than anyone else, so it can float on the water. Under the action of surface tension, oil droplets floating on the water will minimize the surface area, and the circle is the shape with the smallest surface area. So the optimization of floating on the water is round. Not only oil, we usually see rain or dew form round dew on leaves, which is also the result of surface tension.