These cars are not equipped with shocks. They're equipped with struts -- the terms are
not interchangable.
Anyway, that gripe aside, I agree with the previous poster. It sounds like the seat insulator. The front and rear struts have two -- one for the top and one for the bottom. The top and bottom are slightly different but generally they look something like this:
Assuming that's what you're talking about, the ends of the coil fit into the grooves in the insulators which in turn fit into the grooves in the coil seats.
As a note, the upper seat has either "F" or "OUT" with an arrow indicating which way it should be positioned on the strut assembly when all put back together. Be sure that it's positioned so that, when installed, it points outward from the vehicle.