  It has recently been reported that certain thin timelike shells undergo
oscillatory motion in AdS. In this paper, we compute two-point function of a
probe field in the geodesic approximation in such an oscillating shell
background. We confirm that the two-point function exhibits an oscillatory
behaviour following the motion of the shell. We show that similar oscillatory
dynamics is possible when the perfect fluid on the shell has a polytropic
equation of state. Moreover, we show that certain ball like configurations in
AdS also exhibit oscillatory motion and comment on how such a solution can be
smoothly matched to an appropriate exterior solution. We also demonstrate that
the weak energy condition is satisfied for these oscillatory configurations.
