Tensor-valued diffusion encoding can probe diffusion tensor distribution unconfounded by orientation and heterogeneity. Since different cell morphologies may yield similar apparent diffusion tensors, inferring specific microstructural features remains challenging. Further information can be accessed by considering time-dependent diffusion. We show that rotational dependence of spherical tensor encoding, caused by spectral anisotropy, can be prominent on a preclinical scanner. The presented analysis may reveal different microstructural signatures depending on cell shape, which could be relevant for tissue modelling. Our results on fixed monkey brain suggest that brain cells exhibit anisotropic restricted diffusion along all directions, unlike in the cylindrical diffusion model.