  The goal of this work is to show that a ferromagnetic-like domain growth
process takes place within the backbone of the three-dimensional $\pm J$
Edwards-Anderson (EA) spin glass model. To sustain this affirmation we study
the heterogeneities displayed in the out-of-equilibrium dynamics of the model.
We show that both correlation function and mean flipping time distribution
present features that have a direct relation with spatial heterogeneities, and
that they can be characterized by the backbone structure. In order to gain
intuition we analyze the pure ferromagnetic Ising model, where we show the
presence of dynamical heterogeneities in the mean flipping time distribution
that are directly associated to ferromagnetic growing domains. We extend a
method devised to detect domain walls in the Ising model to carry out a similar
analysis in the three-dimensional EA spin glass model. This allows us to show
that there exists a domain growth process within the backbone of this model.
