Surface tension is when molecules of a certain type of liquid are attracted to each other and make the top of the liquid extremely tight. Because of surface tension, soap bubbles always form spheres as the bubbles try to take up the lease amount of space while keeping the same amount of air inside. As you blow air into a bubble, the molecules try to wrap around the air in an attempt to attach to other molecules again, creating a circular shape. Take the shape of a square for example, a round shape will take up less space than any particular square shape.
Bottom of a food container:
Bottom of a Chapstick tube:
I decided to experiment with the bubbles and add both oil & dishwashing liquid into the container…