Why are bubbles spheres?

A bubble’s skin composed of a thin
layer of water molecules sandwiched
between soap molecules. Water has
a high surface tension due to intermolecular
forces. This causes molecules to pull on one
another, trying to minimise the surface area
and be as flat as possible. Soap reduces this
surface tension. However the effect of surface
tension is still present which causes the bubble
‘film’ to be stretched. A sphere is formed
because this shape is the shape with the least
amount of surface area for its available volume.