Clathrin triskelions (three legged molecules like the Isle of Man symbol) assemble together to form a remarkable geodesic sphere, that looks much like a buckyball. This is not surprising, since it is a natural geometric solution to making a round shape with lines or planes.

The clathrin coated vesicles can be as little as 50 nm wide but probably form many diferent sizes. They are produced during cellular processes such as receptor-mediated endocytosis, or when proteins are transported from the ER to the surface.