Sub atomic particles are supposedly point-like, i.e. they are zero dimensional. This is not the same as perfectly spherical, as a sphere is a 3d geometrical object. The only perfect sphere is one that exists as an abstract mathematical object, because in reality trying to build such an object would always fail due to quantum mechanics (specifically the uncertainty principle).
The argument is as follows:
Uncertainty principle is
δxδp>2πhwhere x = position of particle, p = momentum and h = Planck's constant and
δ is the uncertainty on these measurements.
To get a perfect sphere would require perfect placement of each atom constructing it, i.e. there could be no uncertainty on the positions of the atoms. This implies
δx=0. The uncertainty principle then requires that the momentum of the atoms constructing it is completely undefined i.e.
δp=∞Constructing a sphere at the atomic level would require atoms to be bound chemically together; in other words trapped in some kind of electrostatic potential well. A momentum state with infinite uncertainty can tunnel through any finite potential barrier, making it impossible to contain in practice.
This means that the act of placing a particle infinitly precisely (as is required to construct a perfect sphere) makes it physically impossible to contain this particle, meaning such a sphere would never be able to be constructed.