  Colloidal probes immersed in an active bath have been found to behave like
active particles themselves. Here, we use coarse-grained simulations to
investigate the mechanisms behind this behavior. We find that the active motion
of the colloid cannot be simply attributed to the convective motion in the
bath. Instead, the boundary of the probe contributes significantly to these
adopted dynamics by causing active bath particles to spontaneously accumulate
at the probe. This gathering of active bath particles then pushes the probe,
thus promoting its emergent active-particle-like behavior. Furthermore, we find
that the dynamic properties of the probe depend on its size in a non-monotonic
way, which further highlights the non-trivial interplay between probe and bath.
