What is a 0.5x0.4cm bubble?

0.5x0.4cm refers to the shape and size of the bladder.

Some amphiphilic molecules that are not easy to combine into micelles, such as many naturally synthesized surfactants and phospholipids, will spontaneously form a molecular ordered composition with a closed bilayer structure when dispersed in water, which is called vesicle, also known as liposome.

It is used in some cells to store, transport and digest cell products and wastes.