A universe of three dimensions will have only two regular polyhedrons—to fill or tessellate volume without having voids of nothingness—those being tetrahedrons and cubes. The shape of aether particles is likely one of these two forms.
As other substantial particles and objects apparently move without significant friction, the particles of the aether medium must be quite flexible if not compressible…Squidgy!
Their frictionless surfaces along with their vanishingly small mass would generate vanishingly small viscosity.
Natural Philosopher Michael Armstrong explains how he thinks of force as tangible and not theoretical. The EU Model of Cosmology sees the aether medium as a key part of a proper construction of physical reality.