FUNDAMENTAL building blocks of matter, like quarks (which make up the protons and neutrons in atomic nuclei) and electrons (which orbit those nuclei), are called point particles. This is somewhat misleading. It implies that although they have mass, they are also, like mathematical points, zero-dimensional—in other words, they do not take up any space. In the parlance of quantum mechanics, however, to call a particle pointlike is to say no more than that it is elementary, ie, that it is not known to be made up of smaller bits. Nowhere is it stipulated that it cannot have a shape.
Indeed, shape matters. Take the electron, the most manageable of all elementary particles, and thus the most thoroughly studied. According to the Standard Model, a 40-year-old theory which describes the behaviour of all the known elementary particles and forces of nature apart from gravity, an electron's point mass sits amid a cloud of virtual particles which pop in and out of existence—the sort of thing possible in the weird world of quantum mechanics. Theory suggests that this cloud should be an almost perfect sphere. The crucial word, though, is "almost".
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